tests: skip perl tests if NO_PERL is defined

These scripts all test git programs that are written in
perl, and thus obviously won't work if NO_PERL is defined.
We pass NO_PERL to the scripts from the building Makefile
via the GIT-BUILD-OPTIONS file.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index b4e2b4d..e2ef532 100755
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -38,7 +38,7 @@
 	"echo King of the bongo >file &&
 	test_must_fail git commit -m foo -a file"
 
-test_expect_success \
+test_expect_success PERL \
 	"using paths with --interactive" \
 	"echo bong-o-bong >file &&
 	! (echo 7 | git commit -m foo --interactive file)"
@@ -119,7 +119,7 @@
 	"echo 'gak' >file && \
 	 git commit -m 'author' --author 'Rubber Duck <rduck@convoy.org>' -a"
 
-test_expect_success \
+test_expect_success PERL \
 	"interactive add" \
 	"echo 7 | git commit --interactive | grep 'What now'"