Undo main/wWinMain changes in preparation for new method

of doing a startup AVX check.

This reverts commit 4030cff3ec.

src/xenia/app/premake5.lua

@@ -50,20 +50,18 @@ project("xenia-app")
   files({
     "xenia_main.cc",
     "../base/main_"..platform_suffix..".cc",
-    "../base/main_entrypoint_"..platform_suffix..".cc",
   })
 
-  resincludedirs({
-    project_root,
-  })
+  filter("files:xenia_main.cc or ../base/main_"..platform_suffix..".cc")
+    vectorextensions("IA32")  -- Disable AVX for main_win.cc so our AVX check/error can happen.
 
   filter("platforms:Windows")
     files({
       "main_resources.rc",
     })
-
-  filter("files:../base/main_entrypoint_"..platform_suffix..".cc")
-    vectorextensions("IA32")  -- Disable AVX so our AVX check/error can happen.
+  resincludedirs({
+    project_root,
+  })
 
   filter("platforms:Linux")
     links({