buildgcc: Quote command substitution

There are shells where the result of a command substitution is subject
to word splitting (e.g. dash when assigning a value inside an export
statement).

Change-Id: I70a5bc124af7ee621da2bdb4777f3eaba8adafbb
Signed-off-by: Idwer Vollering <vidwer@gmail.com>
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/15820
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
diff --git a/util/crossgcc/buildgcc b/util/crossgcc/buildgcc
index d858919..9eb72f9 100755
--- a/util/crossgcc/buildgcc
+++ b/util/crossgcc/buildgcc
@@ -442,8 +442,8 @@
 set_hostcflags_from_gmp() {
 	# Now set CFLAGS to match GMP CFLAGS but strip out -pedantic
 	# as GCC 4.6.x fails if it's there.
-	export HOSTCFLAGS=$(grep __GMP_CFLAGS $DESTDIR$TARGETDIR/include/gmp.h |cut -d\" -f2 |\
-	    sed s,-pedantic,,)
+	export HOSTCFLAGS="$(grep __GMP_CFLAGS $DESTDIR$TARGETDIR/include/gmp.h |cut -d\" -f2 |\
+	    sed s,-pedantic,,)"
 }
 
 build_GMP() {