Move _POSIX_SOURCE definition

Fixes https://github.com/harfbuzz/harfbuzz/issues/1308

src/hb-blob.cc

@@ -25,6 +25,15 @@
  * Red Hat Author(s): Behdad Esfahbod
  */
 
+
+/* https://github.com/harfbuzz/harfbuzz/issues/1308
+ * http://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html
+ * https://www.oracle.com/technetwork/articles/servers-storage-dev/standardheaderfiles-453865.html
+ */
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
+#endif
+
 #include "hb.hh"
 #include "hb-blob.hh"
 

src/hb.hh

@@ -59,10 +59,6 @@
 # define __EXTENSIONS__ 1
 #endif
 
-#ifndef _POSIX_C_SOURCE
-#define _POSIX_C_SOURCE 200809L
-#endif
-
 #if defined (_MSC_VER) && defined (HB_DLL_EXPORT)
 #define HB_EXTERN __declspec (dllexport) extern
 #endif