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

diff -Naur mysql-5.5.8.orig/include/my_sys.h mysql-5.5.8/include/my_sys.h

--- mysql-5.5.8.orig/include/my_sys.h	2010-12-03 12:58:24.000000000 -0500

+++ mysql-5.5.8/include/my_sys.h	2010-12-20 21:20:12.622190325 -0500

@@ -201,13 +201,8 @@

 #define my_afree(PTR) my_free(PTR)

 #endif /* HAVE_ALLOCA */

-#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 */

+

 extern char *home_dir;			/* Home directory for user */

 extern const char *my_progname;		/* program-name (printed in errors) */

 extern char curr_dir[];		/* Current directory for user */