[gtk-osx] Raise the minimum macOS version to 10.11.

[John Ralls <jralls src gnome org>]

commit 59d77319644fccba5ddf45c73fcc41fd7b4ee30f
Author: John Ralls <jralls ceridwen us>
Date:   Mon Aug 17 12:43:02 2020 -0700

    Raise the minimum macOS version to 10.11.

 jhbuildrc-gtk-osx | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/jhbuildrc-gtk-osx b/jhbuildrc-gtk-osx
index 4a6048e..ce588a6 100644
--- a/jhbuildrc-gtk-osx
+++ b/jhbuildrc-gtk-osx
@@ -27,7 +27,7 @@ import re
 #some variables we'll need defined later
 _default_arch = ""
 _osx_version = 0.0
-_target = '10.9'
+_target = '10.11'
 
 def _popen(cmd_arg):
     from subprocess import Popen, PIPE
@@ -228,7 +228,7 @@ osx_ver()
 #
 # This is the workhorse of the setup. Call this function from
 # .jhbuildrc-custom to configure compile and link flags. Optionally
-# specify a minimum MacOS version (10.9, 10.10, 10.10, etc.) and a list
+# specify a minimum MacOS version (10.11, 10.12, 10.13, etc.) and a list
 # of architectures.
 #
 # The sdk_version does nothing, as since Xcode 5 it is preferred to
@@ -435,8 +435,8 @@ _gtk_osx_default_build = ""
 
 #print "Default Architecture %s\n" % _default_arch
 
-if _osx_version < 9.0:
-    print("Error: Mac OS X 10.9 or newer is required, exiting.")
+if _osx_version < 11.0:
+    print("Error: Mac OS X 10.11 or newer is required, exiting.")
     raise SystemExit
 
 ###### Import Customizations ######