[gimp] Bug 793169 - Current Makefile.am not working on Mac.

[Jehan Pagès <jehanp src gnome org>]

commit d0ede35379051b24a5f84f673b3b8d349478c111
Author: Partha <partha1b gmail com>
Date:   Sun Feb 4 18:49:22 2018 +0100

    Bug 793169 - Current Makefile.am not working on Mac.

 app/widgets/Makefile.am |    7 ++++++-
 tools/Makefile.am       |    7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/app/widgets/Makefile.am b/app/widgets/Makefile.am
index d7013ef..8c3658e 100644
--- a/app/widgets/Makefile.am
+++ b/app/widgets/Makefile.am
@@ -1,5 +1,9 @@
 ## Process this file with automake to produce Makefile.in
 
+if PLATFORM_OSX
+xobjective_c = "-xobjective-c"
+endif
+
 AM_CPPFLAGS = \
         -DISO_CODES_LOCATION=\"$(ISO_CODES_LOCATION)\"         \
         -DISO_CODES_LOCALEDIR=\"$(ISO_CODES_LOCALEDIR)\"       \
@@ -10,7 +14,8 @@ AM_CPPFLAGS = \
        -I$(top_srcdir)/app                                     \
        $(GEGL_CFLAGS)                                          \
        $(GTK_CFLAGS)                                           \
-       -I$(includedir)
+       -I$(includedir)                                         \
+       $(xobjective_c)
 
 noinst_LIBRARIES = libappwidgets.a
 
diff --git a/tools/Makefile.am b/tools/Makefile.am
index 352222d..e841daf 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -4,6 +4,10 @@ AUTOMAKE_OPTIONS = subdir-objects
 
 libgimpbase = $(top_builddir)/libgimpbase/libgimpbase-$(GIMP_API_VERSION).la
 
+if PLATFORM_OSX
+xobjective_c = "-xobjective-c"
+endif
+
 if OS_WIN32
 
 bin_PROGRAMS = \
@@ -113,7 +117,8 @@ AM_CPPFLAGS = \
        -DGIMP_PLUGIN_VERSION=\""$(GIMP_PLUGIN_VERSION)"\"      \
        -I$(top_srcdir)                                         \
        $(GTK_CFLAGS)                                           \
-       -I$(includedir)
+       -I$(includedir)                                         \
+       $(xobjective_c)
 
 EXTRA_DIST = \
        defcheck.py     \