test.bash: Don't build with openssl if we were passed "-tags without_openssl"

test-without-openssl.bash now fails, as it should:

	gocryptfs has been compiled without openssl support but you are still trying to use openssl
	mount failed: exit status 18
	FAIL	github.com/rfjakob/gocryptfs/tests/matrix	1.943s

1 files changed, 2 insertions, 2 deletions

diff --git a/test.bash b/test.bash
index 03eb218..182cdc3 100755
--- a/test.bash
+++ b/test.bash
@@ -27,8 +27,8 @@ for i in $(mount | grep $TESTDIR | cut -f3 -d" "); do
 done
 
 ./build-without-openssl.bash
-# Building with openssl is difficult on OSX, so only do it on Linux.
-if [[ $OSTYPE == linux* ]] ; then
+# Don't build with openssl if we were passed "-tags without_openssl"
+if [[ "$@" != *without_openssl* ]] ; then
 	./build.bash
 fi