buildgcc: move from `..` to $( .. )

Change-Id: I7a095470d408d013a4a915e010c59ea99ca1f1c8
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10484
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Alexander Couzens <lynxis@fe80.eu>
1 file changed