Avoid undefined negation behavior if windowBits is INT_MIN.

deflate.c

diff --git a/deflate.c b/deflate.c
index 0345980..a578b1a 100644
--- a/deflate.c
+++ b/deflate.c
@@ -279,6 +279,8 @@
 
     if (windowBits < 0) { /* suppress zlib wrapper */
         wrap = 0;
+        if (windowBits < -15)
+            return Z_STREAM_ERROR;
         windowBits = -windowBits;
     }
 #ifdef GZIP

inflate.c

diff --git a/inflate.c b/inflate.c
index 2a3c4fe..8acbef4 100644
--- a/inflate.c
+++ b/inflate.c
@@ -168,6 +168,8 @@
 
     /* extract wrap request from windowBits parameter */
     if (windowBits < 0) {
+        if (windowBits < -15)
+            return Z_STREAM_ERROR;
         wrap = 0;
         windowBits = -windowBits;
     }