Remove obsolete HAVE_GCC_VISIBILITY_FEATURE check completely now

cf. f255c3e9 "[API CHANGE] Remove
HAVE_GCC_VISIBILITY_FEATURE, always true"

Change-Id: I958428881f17703d805873a1fe4854896438eb19

configure.ac

@@ -5915,22 +5915,9 @@ fi
 AC_SUBST(HAVE_THREADSAFE_STATICS)
 
 dnl ===================================================================
-dnl visibility and other gcc features
+dnl GCC features
 dnl ===================================================================
 if test "$GCC" = "yes" -o "$COM_IS_CLANG" = TRUE; then
-    if test "$COM" != MSC; then
-        AC_MSG_CHECKING([whether $CC supports -fvisibility=hidden])
-        save_CFLAGS=$CFLAGS
-        CFLAGS="$CFLAGS -Werror -fvisibility=hidden"
-        AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[ return 0; ]])],[ HAVE_GCC_VISIBILITY_FEATURE=TRUE ],[])
-        CFLAGS=$save_CFLAGS
-        if test "$HAVE_GCC_VISIBILITY_FEATURE" = "TRUE"; then
-            AC_MSG_RESULT([yes])
-        else
-            AC_MSG_ERROR([no  This is no longer supported.])
-        fi
-    fi
-
     AC_MSG_CHECKING([whether $CC supports -mno-avx])
     save_CFLAGS=$CFLAGS
     CFLAGS="$CFLAGS -Werror -mno-avx"