crossgcc: jump to crossgcc path before building the toolchain

We use paths relative to that in the buildgcc script.

Change-Id: I2b79c3d2c75088af7e8e362d18a38274352eb965
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/8713
Reviewed-by: Aaron Durbin <adurbin@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

util/crossgcc/buildgcc

@@ -20,6 +20,8 @@
 # Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
 #
 
+cd `dirname $0`
+
 CROSSGCC_DATE="March 8th, 2015"
 CROSSGCC_VERSION="1.27"