buildgcc: Fix string comparison operator

Change-Id: I8ff8d51507dcf12cd554c8b4713074a99e47c11e
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/17942
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/util/crossgcc/buildgcc b/util/crossgcc/buildgcc
index 30e2188..b3deda5 100755
--- a/util/crossgcc/buildgcc
+++ b/util/crossgcc/buildgcc
@@ -572,7 +572,7 @@
 }
 
 build_BINUTILS() {
-	if [ $TARGETARCH == "x86_64-elf" ]; then
+	if [ $TARGETARCH = "x86_64-elf" ]; then
 		ADDITIONALTARGET=",i386-elf"
 	fi
 	CC="$CC" ../binutils-${BINUTILS_VERSION}/configure --prefix=$TARGETDIR \