cmJson.c : Fix typo.

src/cmJson.c

 //
 // cmJsonTest() demonstrates some JSON tree operations.
 //
-JsRC_t cmJsonTest( const char* fn, cmCtx_t* ctx )
+cmJsRC_t cmJsonTest( const char* fn, cmCtx_t* ctx )
 {
   cmJsRC_t      rc  = kOkJsRC;
   cmJsRC_t      rc1 = kOkJsRC;