[gimp] libgimp: don't run defcheck on macOS either.

[Jehan <jehanp src gnome org>]

commit fec1f53745d9e5faeb652a51f34140030cd60240
Author: Jehan <jehan girinstud io>
Date:   Fri Aug 5 00:52:28 2022 +0200

    libgimp: don't run defcheck on macOS either.
    
    Similar to commit f5751ec687.
    See: https://gitlab.gnome.org/GNOME/gimp/-/issues/8274#note_1520297

 libgimp/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/libgimp/meson.build b/libgimp/meson.build
index 8ec49c9d5a..0001e82ccd 100644
--- a/libgimp/meson.build
+++ b/libgimp/meson.build
@@ -519,7 +519,7 @@ else
   endif
 endif
 
-if have_python and not platform_windows
+if have_python and not platform_windows and not platform_osx
   # Verify .def files for Windows.
   # Ironically we only check this on non-Windows platform, since the
   # script expects .so libraries, and I'm not sure that the `nm` tool is