mark gdb7 as broken on Darwin-*-aarch64

[freetolga]

No description provided.

[freetolga]

fdopen is banned on macos sdk
here is one of the errors that prevent the build

In file included from ./gzguts.h:21:
In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:61:
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h:322:7: error: expected identifier or '('
  322 | FILE    *fdopen(int, const char *) __DARWIN_ALIAS_STARTING(__MAC_10_6, __IPHONE_2_0, __DARWIN_ALIAS(fdopen));
      |          ^
./zutil.h:128:33: note: expanded from macro 'fdopen'
  128 | #        define fdopen(fd,mode) NULL /* No fdopen() */
      |                                 ^
/Library/Developer/CommandLineTools/usr/lib/clang/21/include/__stddef_null.h:26:16: note: expanded from macro 'NULL'
   26 | #define NULL ((void*)0)
      |                ^```

[freetolga]

adding

.if ${OPSYS} == "Darwin"
.include "../../devel/zlib/buildlink3.mk"
CONFIGURE_ARGS+= "--with-system-zlib"
.endif

makes both gdb7 and gdb (currently version 10) compile but fail with plist error