gallium: Disable dri2 interface on OSX

Error message:
Undefined symbols for architecture x86_64:
  "_dri_kms_driver_extensions", referenced from:
      _swkmsCreateNewScreen in libdri.a(dri_util.c.o)
  "_galliumdrm_driver_extensions", referenced from:
      _dri2CreateNewScreen in libdri.a(dri_util.c.o)
ld: symbol(s) not found for architecture x86_64

Fixes: b6f7a4836a ("dri: Fill in the driver extensions for the legacy createNewScreen paths")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6519

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17784>

meson.build

@@ -1692,6 +1692,9 @@ endif
 if with_dri
   pre_args += '-DHAVE_DRI'
 endif
+if with_dri2
+  pre_args += '-DHAVE_DRI2'
+endif
 if with_gallium_drisw_kms
   pre_args += '-DHAVE_DRISW_KMS'
 endif

src/gallium/frontends/dri/dri_util.c

@@ -963,6 +963,8 @@ const __DRIcoreExtension driCoreExtension = {
     .unbindContext              = driUnbindContext
 };
 
+#if HAVE_DRI2
+
 /** DRI2 interface */
 const __DRIdri2Extension driDRI2Extension = {
     .base = { __DRI_DRI2, 4 },
@@ -992,6 +994,8 @@ const __DRIdri2Extension swkmsDRI2Extension = {
     .createNewScreen2           = driCreateNewScreen2,
 };
 
+#endif
+
 const __DRIswrastExtension driSWRastExtension = {
     .base = { __DRI_SWRAST, 4 },