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

runit/runit_lib.h

@@ -25,9 +25,7 @@ OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-#if __GNUC_PREREQ(4,1)
-# pragma GCC visibility push(hidden)
-#endif
+PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
 extern unsigned byte_chr(char *s,unsigned n,int c);
 
@@ -100,6 +98,4 @@ struct ERR_svstatus_must_be_20_bytes {
 	char ERR_svstatus_must_be_20_bytes[sizeof(svstatus_t) == 20 ? 1 : -1];
 };
 
-#if __GNUC_PREREQ(4,1)
-# pragma GCC visibility pop
-#endif
+POP_SAVED_FUNCTION_VISIBILITY