ui/cocoa: release filetypes NSArray in non-Metal file-browser open path

ui_browser_window_cocoa_open has two branches for constructing the
allowed-file-types list passed to -[NSOpenPanel setAllowedFileTypes:]:

    #ifdef HAVE_COCOA_METAL
       [panel setAllowedFileTypes:@[BOXSTRING(...), BOXSTRING(...)]];
    #else
       NSArray *filetypes = [[NSArray alloc] initWithObjects:..., nil];
       [panel setAllowedFileTypes:filetypes];
    #endif

The HAVE_COCOA_METAL branch uses @[...] literal syntax, which
creates an autoreleased NSArray - released by the enclosing
autorelease pool.  The #else branch uses explicit alloc+init,
which returns +1 retained; setAllowedFileTypes: retains its own
reference, so after the call returns we must release the local
or it leaks.

This file compiles under MRC per Makefile.common ~line 1654
('MRC-written Cocoa code (ui_cocoa.m et al.)'), and the fix macro
RARCH_RELEASE from libretro-common/include/defines/cocoa_defines.h
expands to [(x) release] on MRC and to ((void)0) under ARC, so
adding it is safe for both build matrices even though this file
is MRC-only today.

The leak fires every time the user opens a filtered file dialog
(Load Core, Load Content).  NSArray with two BOXSTRING'd
NSStrings is a few dozen bytes per occurrence; not catastrophic,
but a leaks(1) run would flag it every time.

Thread-safety: unchanged.  ui_browser_window_cocoa_open runs on
the main AppKit thread.

Scope: the rest of this file's menu-building code (lines 1220+)
is consistent and correctly uses the alloc-then-RARCH_RELEASE
pattern via the cocoa_menu_item_with_action helper and the per-
menu builder functions.  cocoa_create_menu_bar's six menubar
items all pair alloc+init with RARCH_RELEASE.  The file_browser
open path was the one outlier.

Author: LibretroAdmin

ui/drivers/ui_cocoa.m

@@ -172,8 +172,17 @@ static bool ui_browser_window_cocoa_open(ui_browser_window_state_t *state)
 #ifdef HAVE_COCOA_METAL
       [panel setAllowedFileTypes:@[BOXSTRING(state->filters), BOXSTRING(state->filters_title)]];
 #else
+      /* Under MRC (ui_cocoa.m is built without -fobjc-arc per the
+       * top-level Makefile; see Makefile.common ~line 1654), the
+       * local 'filetypes' is +1 from alloc+initWithObjects.
+       * setAllowedFileTypes: retains its own reference, so after
+       * the call returns we must release the local +1 or it leaks
+       * every time the file picker opens with a filter.  The
+       * HAVE_COCOA_METAL branch above uses @[...] literal syntax
+       * which is already autoreleased. */
       NSArray *filetypes = [[NSArray alloc] initWithObjects:BOXSTRING(state->filters), BOXSTRING(state->filters_title), nil];
       [panel setAllowedFileTypes:filetypes];
+      RARCH_RELEASE(filetypes);
 #endif
    }