[Premake] Fixing issues during build on Linux

- Lack of AVX2 extension (should be done differently in the future)
- Disable deprecated-volatile warning
- Added missing override in posix EventInfo

premake5.lua

@@ -113,6 +113,9 @@ filter("platforms:Linux")
     "rt",
   })
 
+filter({"platforms:Linux"})
+  vectorextensions("AVX2")
+
 filter({"platforms:Linux", "kind:*App"})
   linkgroups("On")
 

src/xenia/base/premake5.lua

@@ -8,6 +8,10 @@ project("xenia-base")
   links({
     "fmt",
   })
+  filter({"toolset:gcc or clang"})
+    buildoptions({
+      "-Wno-deprecated-volatile"
+    })
   defines({
   })
   local_platform_files()

src/xenia/base/threading_posix.cc

@@ -905,7 +905,7 @@ class PosixEvent : public PosixConditionHandle<Event> {
   ~PosixEvent() override = default;
   void Set() override { handle_.Signal(); }
   void Reset() override { handle_.Reset(); }
-  EventInfo Query() {
+  EventInfo Query() override {
     EventInfo result{};
     assert_always();
     return result;