PKG_CONFIG is hardcoded to /usr/bin/pkg-config which is not cross
compile safe and ends up with build errors especially on hosts where
pkgconf is used it ends up with errors like
/usr/bin/pkg-config: line 11: exec: pkgconf: not found
/usr/bin/pkg-config: line 11: exec: pkgconf: not found
Override it to use own native pkg-config which can deal with sysroot
correctly
Signed-off-by: Khem Raj <raj.khem@gmail.com>