Bring us closer to working with MinGW again.

The biggest obstacle right now deals with FFMPEG. I insist on being able to utilize the git clone/submodule (5_1_0) section. I'm just struggling with the commands.

As part of this commit, some linux files are restored in the compilation chain. This is for consistency with the old Makefile approach.

Assistance will be needed at this point to complete MinGW support.

src/archutils/Win32/arch_setup.h

@@ -89,8 +89,10 @@ struct tm *my_localtime_r( const time_t *timep, struct tm *result );
 #define localtime_r my_localtime_r
 struct tm *my_gmtime_r( const time_t *timep, struct tm *result );
 #define gmtime_r my_gmtime_r
+#if defined(_MSC_VER)
 void my_usleep( unsigned long usec );
 #define usleep my_usleep
+#endif
 
 // Missing stdint types:
 #if !defined(__MINGW32__) // MinGW headers define these for us