Remove variadic macros test from configure

This is useless, all still supported compilers except ancient MSVS
versions (for which configure is not used anyhow) support variadic
macros, so don't waste time testing for them.

Note that the checks for HAVE_VARIADIC_MACROS in the sources are still
left because it is still possible to explicitly disable variadic macros
support using --disable-vararg_macros for strict C++98 compatibility.

configure

@@ -19954,63 +19954,7 @@ $as_echo "$wx_cv_type_va_list_lvalue" >&6; }
     fi
 fi
 
-if test "$wxUSE_VARARG_MACROS" = "yes"; then
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports variadic macros" >&5
-$as_echo_n "checking whether the compiler supports variadic macros... " >&6; }
-if ${wx_cv_have_variadic_macros+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-
-                        ac_ext=cpp
-ac_cpp='$CXXCPP $CPPFLAGS'
-ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
-ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
-ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
-
-        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-
-                    #include <stdio.h>
-                    #define test(fmt, ...) printf(fmt, __VA_ARGS__)
-
-int
-main ()
-{
-
-                    test("%s %d %p", "test", 1, 0);
-
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
-  wx_cv_have_variadic_macros=yes
-else
-  wx_cv_have_variadic_macros=no
-
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-        ac_ext=c
-ac_cpp='$CPP $CPPFLAGS'
-ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
-ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
-ac_compiler_gnu=$ac_cv_c_compiler_gnu
-
-
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $wx_cv_have_variadic_macros" >&5
-$as_echo "$wx_cv_have_variadic_macros" >&6; }
-
-if test $wx_cv_have_variadic_macros = "yes"; then
-    $as_echo "#define HAVE_VARIADIC_MACROS 1" >>confdefs.h
-
-fi
-
-else
+if test "$wxUSE_VARARG_MACROS" != "yes"; then
     $as_echo "#define wxNO_VARIADIC_MACROS 1" >>confdefs.h
 
 fi