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_local.h

@@ -70,6 +70,8 @@ qboolean Sys_PIDIsRunning( int pid );
 
 qboolean Sys_OpenFolderInPlatformFileManager( const char *path );
 
+qboolean Sys_SetMaxFileLimit( void );
+
 #ifdef PROTOCOL_HANDLER
 char *Sys_ParseProtocolUri( const char *uri );
 #endif