Fix Android release build after enabling -Wl,-z,defs (#3004)

The LWIP_DEBUG option is not applied consistently, LwIP itself uses
 #ifdef LWIP_DEBUG but one location in CHIP uses #if LWIP_DEBUG.

/home/spang/sdk/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/armv7a-linux-androideabi24-clang++ -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=softfp -mthumb -Wl,-O2 -Wl,--gc-sections -Os -fPIC -Wl,--fatal-warnings -Werror -Wl,-z,defs -fdiagnostics-color -Wl,-Map,android_arm/lib/jni/armeabi-v7a/libSetupPayloadParser.map -Wl,--gc-sections -Wl,--start-group android_arm/obj/src/setup_payload/java/libSetupPayloadParser.SetupPayloadParser-JNI.cpp.o android_arm/obj/src/lwip/standalone/lwip.sys_arch.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.def.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.dns.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.inet_chksum.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.init.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.ip.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.mem.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.memp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.netif.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.pbuf.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.raw.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.stats.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.sys.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.tcp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.tcp_in.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.tcp_out.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.timeouts.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/lwip.udp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.autoip.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.dhcp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.etharp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.icmp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.igmp.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.ip4.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.ip4_addr.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv4/lwip.ip4_frag.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.dhcp6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.ethip6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.icmp6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.inet6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.ip6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.ip6_addr.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.ip6_frag.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.ip6_route_table.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.mld6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/core/ipv6/lwip.nd6.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.api_lib.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.api_msg.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.err.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.if.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.netbuf.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.netdb.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.netifapi.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.sockets.c.o android_arm/obj/third_party/lwip/repo/lwip/src/api/lwip.tcpip.c.o android_arm/obj/third_party/lwip/repo/lwip/src/netif/lwip.ethernet.c.o android_arm/obj/third_party/lwip/repo/lwip/src/netif/lwip.lowpan6.c.o android_arm/lib/libCHIP.a android_arm/obj/src/setup_payload/lib/libSetupPayload.a android_arm/obj/src/lib/core/lib/libChipCore.a android_arm/obj/src/app/lib/libCHIPDataModel.a android_arm/obj/src/lib/support/lib/libSupportLayer.a android_arm/lib/libnlfaultinjection.a android_arm/obj/src/system/lib/libSystemLayer.a android_arm/obj/src/ble/lib/libBleLayer.a android_arm/obj/src/inet/lib/libInetLayer.a  -llog -Wl,--end-group -o android_arm/lib/jni/armeabi-v7a/libSetupPayloadParser.so -shared
../../third_party/lwip/repo/lwip/src/core/netif.c:0: error: undefined reference to 'gLwIP_DebugFlags'
../../third_party/lwip/repo/lwip/src/core/netif.c:0: error: undefined reference to 'gLwIP_DebugFlags'
../../third_party/lwip/repo/lwip/src/core/netif.c:0: error: undefined reference to 'gLwIP_DebugFlags'
../../third_party/lwip/repo/lwip/src/core/netif.c:0: error: undefined reference to 'gLwIP_DebugFlags'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
diff --git a/src/lwip/BUILD.gn b/src/lwip/BUILD.gn
index 5807e88..ffcd486 100644
--- a/src/lwip/BUILD.gn
+++ b/src/lwip/BUILD.gn
@@ -50,8 +50,10 @@
 
   defines = [ "HAVE_LWIP_UDP_BIND_NETIF=1" ]
   if (lwip_platform != "external") {
-    # Automatically enable LWIP_DEBUG for internal is_debug builds.
-    defines += [ "LWIP_DEBUG=${is_debug}" ]
+    if (is_debug) {
+      # Automatically enable LWIP_DEBUG for internal is_debug builds.
+      defines += [ "LWIP_DEBUG=1" ]
+    }
 
     if (current_os == "android") {
       defines += [ "LWIP_NO_STDINT_H=1" ]
diff --git a/src/lwip/standalone/sys_arch.c b/src/lwip/standalone/sys_arch.c
index a220dd1..a356307 100644
--- a/src/lwip/standalone/sys_arch.c
+++ b/src/lwip/standalone/sys_arch.c
@@ -687,7 +687,7 @@
 }
 #endif
 
-#if LWIP_DEBUG
+#ifdef LWIP_DEBUG
 
 unsigned char gLwIP_DebugFlags = 0;