misc: source_set -> pw_source_set

This updates several uses of GN's builtin source_set to use
pw_source_set instead.

Change-Id: I067ad500016db7b96ba9ec5a057680639e6c6f73
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/17640
Reviewed-by: Armando Montanez <amontanez@google.com>
Reviewed-by: Ewout van Bekkum <ewout@google.com>
Commit-Queue: Alexei Frolov <frolv@google.com>
diff --git a/pw_bloat/BUILD.gn b/pw_bloat/BUILD.gn
index 7e4f29c..72b55f5 100644
--- a/pw_bloat/BUILD.gn
+++ b/pw_bloat/BUILD.gn
@@ -30,7 +30,7 @@
   sources = [ "bloat_this_binary.cc" ]
 }
 
-source_set("base_main") {
+pw_source_set("base_main") {
   sources = [ "base_main.cc" ]
 }
 
diff --git a/pw_fuzzer/BUILD.gn b/pw_fuzzer/BUILD.gn
index 130a05b..bacee77 100644
--- a/pw_fuzzer/BUILD.gn
+++ b/pw_fuzzer/BUILD.gn
@@ -76,7 +76,7 @@
   public_deps = [ "$dir_pw_log" ]
 }
 
-source_set("run_as_unit_test") {
+pw_source_set("run_as_unit_test") {
   configs = [ ":default_config" ]
   sources = [ "pw_fuzzer_disabled.cc" ]
   deps = [
diff --git a/pw_log_null/BUILD.gn b/pw_log_null/BUILD.gn
index e480d0e..8fab307 100644
--- a/pw_log_null/BUILD.gn
+++ b/pw_log_null/BUILD.gn
@@ -15,6 +15,7 @@
 # gn-format disable
 import("//build_overrides/pigweed.gni")
 
+import("$dir_pw_build/target_types.gni")
 import("$dir_pw_docgen/docs.gni")
 import("$dir_pw_unit_test/test.gni")
 config("config") {
@@ -25,7 +26,7 @@
   visibility = [ ":*" ]
 }
 
-source_set("pw_log_null") {
+pw_source_set("pw_log_null") {
   public_configs = [ ":config" ]
   public = [ "public_overrides/pw_log_backend/log_backend.h" ]
   sources = [ "public/pw_log_null/log_null.h" ]