build: avoid calling undefined macro.

This line was reporting "command not found" and should not be a
problem, as there's a check for the same thing later on.

Signed-off-by: Diego Elio Pettenò <flameeyes@flameeyes.eu>
diff --git a/configure.ac b/configure.ac
index 42d7b57..deb5fd4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -15,7 +15,6 @@
 AC_PROG_INSTALL
 LT_INIT
 AC_PROG_LIBTOOL
-CHECK_GCC_FVISIBILITY
 
 AC_CONFIG_MACRO_DIR([m4])