crossgcc: Save the script itself when cross build is over.

In case that the new toolchains don't work well, we can trace back
and reproduce the old tools by checking the xgcc folder. It is useful
when my team members need to get my old toolchains on their own host
machines.

Change-Id: I54e4bc6afcfbbf622165af6eae27bbb6efc2e8cc
Signed-off-by: Zheng Bao <zheng.bao@amd.com>
Signed-off-by: zbao <fishbaozi@gmail.com>
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/2247
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

util/crossgcc/buildgcc

@@ -595,6 +595,9 @@ test -r $IASL_DIR/generate/unix/.failed && printf "${RED}failed${NC}\n" || \
 test -r $IASL_DIR/generate/unix/.failed && exit 1
 fi
 
+rm -f $DESTDIR$TARGETDIR/$0.commit.*
+cp $0 $DESTDIR$TARGETDIR/"$0.commit.`git describe`"
+
 if [ $SAVETEMPS -eq 0 ]; then
 	printf "Cleaning up... "
 	rm -rf ${GMP_DIR} build-gmp