Raise a compile error for implicit declarations in CGO.

go/cgzip/adler32.go

@@ -5,6 +5,7 @@
 package cgzip
 
 /*
+#cgo CFLAGS: -Werror=implicit
 #cgo pkg-config: zlib
 
 #include "zlib.h"

go/cgzip/crc32.go

@@ -5,6 +5,7 @@
 package cgzip
 
 /*
+#cgo CFLAGS: -Werror=implicit
 #cgo pkg-config: zlib
 
 #include "zlib.h"

go/cgzip/reader.go

@@ -5,6 +5,7 @@
 package cgzip
 
 /*
+#cgo CFLAGS: -Werror=implicit
 #cgo pkg-config: zlib
 
 #include "zlib.h"

go/cgzip/writer.go

@@ -7,6 +7,7 @@ package cgzip
 // See http://www.zlib.net/zlib_how.html for more information on this
 
 /*
+#cgo CFLAGS: -Werror=implicit
 #cgo pkg-config: zlib
 
 #include "zlib.h"

go/mysql/mysql.go

@@ -5,6 +5,7 @@
 package mysql
 
 /*
+#cgo CFLAGS: -Werror=implicit
 #cgo pkg-config: gomysql
 #include <stdlib.h>
 #include <mysqld_error.h>