Split off ROM set checking from pc_init_modules()

Everything else isn't needed for the manager

src/unix/unix.c

@@ -1228,11 +1228,12 @@ main(int argc, char **argv)
     ret = pc_init(argc, argv);
     if (ret == 0)
         return 0;
-    if (!pc_init_modules()) {
+    if (!pc_init_roms()) {
         ui_msgbox_header(MBX_FATAL, L"No ROMs found.", L"86Box could not find any usable ROM images.\n\nPlease download a ROM set and extract it into the \"roms\" directory.");
         SDL_Quit();
         return 6;
     }
+    pc_init_modules();
 
     for (uint8_t i = 1; i < GFXCARD_MAX; i++)
         gfxcard[i]  = 0;