Fix opensource build test.

It's a string of unit tests, so size should actually be small. Setting timeout
to long means we have 15 minutes to test everything, which should fit for now.

Also fixes a compile error.

Once this goes in, TAP should start running our tests again.
	Change on 2014/12/17 by ctiller <ctiller@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82395309

test/core/security/json_token_test.c

@@ -214,7 +214,8 @@ static cJSON *parse_json_part_from_jwt(const char *str, size_t len) {
   slice = grpc_base64_decode(b64, 1);
   GPR_ASSERT(!GPR_SLICE_IS_EMPTY(slice));
   decoded = gpr_malloc(GPR_SLICE_LENGTH(slice) + 1);
-  strncpy(decoded, GPR_SLICE_START_PTR(slice), GPR_SLICE_LENGTH(slice));
+  strncpy(decoded, (const char *)GPR_SLICE_START_PTR(slice),
+          GPR_SLICE_LENGTH(slice));
   decoded[GPR_SLICE_LENGTH(slice)] = '\0';
   json = cJSON_Parse(decoded);
   gpr_free(b64);