delete jsmn_test.exe when doing make clean
delete jsmn_test.exe when doing make clean

When building the jsmn test suite on Windows via mingw, the output executable is called "jsmn_test.exe" instead of just "jsmn_test".

dgervais/jsmn,zserge/jsmn,aphuse/jsmn,hawkhsieh/jsmn,ditupao/jsmn