"extern int errno" is just a really bad idea.

diff -up mariadb-5.5.33a/include/my_sys.h.p1 mariadb-5.5.33a/include/my_sys.h
--- mariadb-5.5.33a/include/my_sys.h.p1	2013-10-10 13:37:11.391507810 +0200
+++ mariadb-5.5.33a/include/my_sys.h	2013-10-10 13:37:57.395519715 +0200
@@ -190,13 +190,7 @@ extern void my_large_free(uchar *ptr);
 #define my_safe_alloca(size, min_length) ((size <= min_length) ? my_alloca(size) : my_malloc(size,MYF(MY_FAE)))
 #define my_safe_afree(ptr, size, min_length) ((size <= min_length) ? my_afree(ptr) : my_free(ptr))
 
-#ifndef errno				/* did we already get it? */
-#ifdef HAVE_ERRNO_AS_DEFINE
-#include <errno.h>			/* errno is a define */
-#else
-extern int errno;			/* declare errno */
-#endif
-#endif					/* #ifndef errno */
+#include <errno.h>                     /* errno is a define */
 extern char *home_dir;			/* Home directory for user */
 extern MYSQL_PLUGIN_IMPORT char  *mysql_data_home;
 extern const char *my_progname;		/* program-name (printed in errors) */