Rename SUPPORT__BUILTIN_EXPECT to HAVE_BUILTIN_EXPECT.

diff --git a/m4/attributes.m4 b/m4/attributes.m4
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -229,7 +229,7 @@ AC_DEFUN([CC_FUNC_EXPECT], [
     ])
 
   AS_IF([test "x$cc_cv_func_expect" = "xyes"],
-    [AC_DEFINE([SUPPORT__BUILTIN_EXPECT], 1,
+    [AC_DEFINE([HAVE_BUILTIN_EXPECT], 1,
      [Define this if the compiler supports __builtin_expect() function])
      $1],
     [$2])