[linux_platform] Implement a bunch of missing functions necessaries to make Xenia build correctly under Linux

With this part fixed and a function readapted from the original codebase to fix the different signature, we should have a compiling Linux build now.

src/xenia/base/clock_posix.cc

@@ -53,4 +53,5 @@ uint64_t Clock::QueryHostUptimeMillis() {
   return host_tick_count_platform() * 1000 / host_tick_frequency_platform();
 }
 
+uint64_t Clock::QueryHostInterruptTime() { return host_tick_count_platform(); }
 }  // namespace xe