pmt: Improvements for developers

- Android.bp was written to be included in ROMs/recoveries etc. in Android build system.
 - Macros have been added to simplify feature creation.
 - Some bug fixes (for JSON and pmt).

srclib/libhelper/src/Classes.cpp

@@ -58,10 +58,18 @@ Logger::~Logger() {
         fd != -1)
       close(fd);
     else {
+#ifdef ANDROID_BUILD
+      LoggingProperties::setLogFile("/tmp/last_pmt_logs.log")
+#else
       LoggingProperties::setLogFile("last_logs.log");
+#endif
       LOGN(HELPER, INFO) << "Cannot create log file: " << _logFile << ": "
                          << strerror(errno)
+#ifdef ANDROID_BUILD
+                         << " New logging file: /tmp/last_pmt_logs.log (this file)."
+#else
                          << " New logging file: last_logs.log (this file)."
+#endif
                          << std::endl;
     }
   }