[glib] build: Loosen --enable-compile-warnings check

[Philip Withnall <pwithnall src gnome org>]

commit 22700faf88bdf7be0bbd8dad658f0d08816a7c51
Author: Philip Withnall <withnall endlessm com>
Date:   Thu Aug 3 11:55:23 2017 +0100

    build: Loosen --enable-compile-warnings check
    
    Instead of requiring --enable-compile-warnings or
    --enable-compile-warnings=yes, allow any value which is not ‘no’. This
    enables compile warnings for --enable-compile-warnings=maximum or
    --enable-compile-warnings=error, which are common values for other GNOME
    projects. While we don’t change our behaviour for [yes, maximum, error],
    at least it means the warnings are enabled now, rather than disabled.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index fe9438f..5c2bf8e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3390,7 +3390,7 @@ AC_ARG_ENABLE(compile-warnings,
               [AS_HELP_STRING([--disable-compile-warnings],
                               [Don't use builtin compiler warnings])],,
                              enable_compile_warnings=yes)
-AS_IF([test "x$enable_compile_warnings" = xyes], [
+AS_IF([test "x$enable_compile_warnings" != xno], [
   CC_CHECK_FLAGS_APPEND([GLIB_WARN_CFLAGS], [CFLAGS], [\
    -Wall -Wstrict-prototypes -Werror=declaration-after-statement \
    -Werror=missing-prototypes -Werror=implicit-function-declaration \