package/Makefile.in: pass '-g0' explicitly if !BR2_ENABLE_DEBUG

package/Makefile.in: pass '-g0' explicitly if !BR2_ENABLE_DEBUG

If BR2_ENABLE_DEBUG is not set, Buildroot did not pass any flag
to control debug level. This means that the build system of the package
itself would control it.

Instead, provide an explicit '-g0' (no debugging symbols) to get consistent
behavior across packages.

Suggested-by: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>