BUG 11763056 - 55721: AIX 5.1.50 build failing, cannot locate bzero

The problem is that although AIX implements bzero, its prototype
is not declared by default. Since AC_CHECK_FUNC(bzero) succeeds
even though a prototype is not declared, this breaks compilation
in C++ files where a prototype is required.

The solution is to only use bzero if a prototype is also declared.

configure.in:
  Check if bzero is declared. No need to specify the includes,
  unisted.h and strings.h are already part of AC_INCLUDES_DEFAULT.

configure.in

@@ -2042,12 +2042,7 @@ MYSQL_TYPE_QSORT
 AC_FUNC_UTIME_NULL
 AC_FUNC_VPRINTF
 
-AC_CHECK_DECLS([fdatasync],,,
-[
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-])
+AC_CHECK_DECLS([fdatasync, bzero])
 
 AC_CHECK_FUNCS(alarm bfill bmove bsearch bzero \
   chsize cuserid fchmod fcntl \

include/m_string.h

@@ -58,7 +58,7 @@
 # define bfill(A,B,C)           memset((A),(C),(B))
 #endif
 
-#if !defined(bzero) && !defined(HAVE_BZERO)
+#if !defined(bzero) && (!defined(HAVE_BZERO) || !defined(HAVE_DECL_BZERO))
 # define bzero(A,B)             memset((A),0,(B))
 #endif