[gtk-mac-integration] Provide gtk-mac-integration.pc for backwards compatibility.

[John Ralls <jralls src gnome org>]

commit 1b2a1d0a5d44237b2c4e5b177f3bfe7637d286c6
Author: John Ralls <jralls ceridwen us>
Date:   Thu May 21 11:45:51 2015 -0700

    Provide gtk-mac-integration.pc for backwards compatibility.
    
    gtk-mac-integration.pc is a copy of gtk-mac-integration-gtk2.pc unless
    only gtk3 is present or configured in which case it's a copy of
    gtk-mac-integration-gtk3.pc.
    
    The relaxes the need for applications to fix their configure.ac to update
    to gtk-mac-integration-gtk2.pc or gtk-mac-integration-gtk3.pc in
    configure.ac: It will work in all cases for gtk2 applications as long as
    gtk2 is available and configured when gtk-mac-integration is built, but
    will work for gtk3 applications only in those cases where only gtk3 is
    present or configured.
    
    It's still advisable for all applications to specify which
    gtk-mac-integration they need for cases like MacPorts where they might
    be built with both present and with gtk-mac-integration-2.0.7.

 README           |   14 ++++++++++++++
 data/Makefile.am |    9 ++++++++-
 2 files changed, 22 insertions(+), 1 deletions(-)
---
diff --git a/README b/README
index 9cd19da..66a1238 100644
--- a/README
+++ b/README
@@ -34,6 +34,20 @@ http://live.gnome.org/GTK%2B/OSX/Integration.
 
 For more information about the Gtk-OSX project, please visit our
 webpage at http://gtk-osx.sourceforge.net/
+Gtk-mac-integration may be built for either Gtk+-2, Gtk+-3, or since
+version 2.0.7 both. Because it's not possible to link both
+libgtk-quartz-2.0.dylib and libgtk-3.dylib, from version 2.0.7 on it
+builds libgtkmacintegration-gtk2.dylib and/or
+libgtkmacintegration-gtk3.dylib and provides separate pkgconfig files,
+gtk-mac-integration-gtk2.pc and gtk-mac-integration-gtk3.pc, for the
+respective gtk library versions. Since version 2.0.8 it also provides
+gtk-mac-integration.pc which is a copy of gtk-mac-integration-gtk2.pc
+*unless only libgtk-mac-integration-gtk3 is built*. This is to avoid
+breakage of applications last updated before version
+2.0.7. Application maintainers are urged not to depend on this as it
+may not work in all environments and to update their applications to
+use the appropriate version-specific pc file.
+
 
 MAINTAINER NOTE:
 
diff --git a/data/Makefile.am b/data/Makefile.am
index 1eb4792..7c3edd7 100644
--- a/data/Makefile.am
+++ b/data/Makefile.am
@@ -1,11 +1,18 @@
 EXTRA_DIST = gtk-mac-integration-gtk3.pc.in gtk-mac-integration-gtk2.pc.in
 
-pkgconfig_DATA =
+pkgconfig_DATA = gtk-mac-integration.pc
 
 if WITH_GTK3
 pkgconfig_DATA += gtk-mac-integration-gtk3.pc
+if !WITH_GTK2
+default_pc_file = gtk-mac-integration-gtk3.pc
+endif
 endif
 
 if WITH_GTK2
 pkgconfig_DATA += gtk-mac-integration-gtk2.pc
+default_pc_file = gtk-mac-integration-gtk2.pc
 endif
+
+gtk-mac-integration.pc: ${default_pc_file}
+       cp ${default_pc_file} $@