Set the maximum file limit for POSIX systems

Resolves an issue where the macOS application's dylibs could not be
loaded because there were too many maps; on macOS the default maximum
number of open files is 256.

code/sys/sys_main.c

@@ -823,6 +823,7 @@ int main( int argc, char **argv )
 #endif
 
 	Sys_PlatformInit( );
+	Sys_SetMaxFileLimit( );
 
 	// Set the initial time base
 	Sys_Milliseconds( );