kbuild: New 'cc-fullversion' macro

Prints a six-digit string including the GCC patchlevel.  Also fix
the 'usage' comment for cc-version.

Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2 files changed