crossgcc/Makefile: clean more, add distclean target

Update the clean target to remove the intermediate files.  These should
get removed automatically, but if the build stops in the middle, or if
the -t command is used for buildgcc, they can be left in the directory.

Add a distclean target that removes the downloaded tarballs as well as
everything else.

Change-Id: I6ea19e7a499b0c313c1d2eff7e36386204ec834e
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: http://review.coreboot.org/10621
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
1 file changed