*: make "pragma GCC visibility push(hidden)" less ugly

diff --git a/include/xatonum.h b/include/xatonum.h
index 86a3472..ee816ef 100644
--- a/include/xatonum.h
+++ b/include/xatonum.h
@@ -7,9 +7,7 @@
  * Licensed under GPLv2, see file LICENSE in this tarball for details.
  */
 
-#if __GNUC_PREREQ(4,1)
-# pragma GCC visibility push(hidden)
-#endif
+PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
 /* Provides extern declarations of functions */
 #define DECLARE_STR_CONV(type, T, UT) \
@@ -171,6 +169,4 @@
 
 double bb_strtod(const char *arg, char **endp) FAST_FUNC;
 
-#if __GNUC_PREREQ(4,1)
-# pragma GCC visibility pop
-#endif
+POP_SAVED_FUNCTION_VISIBILITY