gconf: fix buildpaths QA issue

gconf: fix buildpaths QA issue

The build paths come from debug mode, and GConf is effectively
unmaintained these days anyway. So explicitly disable debug
to fix build paths QA issue.

The minimum still keeps Glib check and assert which can result in
crashes if bad data is passed to the API.

[YOCTO #7058]

(From OE-Core rev: 63ff01539914fe36a91196c792e5404d668b6b81)

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>