test: Add test to verify helpers used for backing file name parsing

Add two test cases to verify that the helpers split and parse the
backing store components properly.

tests/virstringtest.c

@@ -597,6 +597,9 @@ mymain(void)
     const char *tokens7[] = { "The", "quick", "brown", "fox", "", NULL };
     TEST_SPLIT("The quick brown fox ", " ", 0, tokens7);
 
+    const char *tokens8[] = { "gluster", "rdma", NULL };
+    TEST_SPLIT("gluster+rdma", "+", 2, tokens8);
+
     if (virtTestRun("strdup", testStrdup, NULL) < 0)
         ret = -1;
 

tests/viruritest.c

@@ -173,6 +173,7 @@ mymain(void)
     TEST_PARSE("test://127.0.0.1:123/system", "test", "127.0.0.1", 123, "/system", NULL, NULL, NULL, NULL);
     TEST_PARSE("test://[::1]:123/system", "test", "::1", 123, "/system", NULL, NULL, NULL, NULL);
     TEST_PARSE("test://[2001:41c8:1:4fd4::2]:123/system", "test", "2001:41c8:1:4fd4::2", 123, "/system", NULL, NULL, NULL, NULL);
+    TEST_PARSE("gluster+rdma://example.com:1234/gv0/vol.img", "gluster+rdma", "example.com", 1234, "/gv0/vol.img", NULL, NULL, NULL, NULL);
 
     virURIParam params1[] = {
         { (char*)"foo", (char*)"one", false },