regress/buildlink-transform: fix quoted-arg test

In the shell command language, the 'case' statement applies different
expansion rules to the subject and the patterns. In particular, the
quotes are removed from the subject but not the patterns.

regress/buildlink-transform/Makefile

@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.23 2024/11/24 08:34:45 rillig Exp $
+# $NetBSD: Makefile,v 1.24 2024/11/24 08:58:29 rillig Exp $
 #
 # Run many buildlink transform tests in a single regression test to avoid
 # having to keep creating the wrapper scripts over and over again.
@@ -78,7 +78,7 @@ TEST_RESULT=	runtest=`${SETENV} ${REGRESS_ENV} regress $$test`;	\
 		${ECHO} "(${.TARGET}) got:      $$runtest";		\
 		${ECHO} "(${.TARGET}) expected: $$expected";		\
 		case $$runtest in					\
-		$$expected)						\
+		$$expected | "$$expected")				\
 			${ECHO} "(${.TARGET}) result:   PASS";		\
 			${ECHO} "${.TARGET}" >> ${PASSED_TESTS};	\
 			;;						\