[iOS] Set --auto-activate-custom-fonts for ibtool compile.

pylib/gyp/mac_tool.py

Index: pylib/gyp/mac_tool.py
diff --git a/pylib/gyp/mac_tool.py b/pylib/gyp/mac_tool.py
index aca7383b4d4a8d0c3b1630eeb5b83731423c2785..913612b2b91a2a2831624d3286a6a70d9f029acd 100755
--- a/pylib/gyp/mac_tool.py
+++ b/pylib/gyp/mac_tool.py
@@ -80,7 +80,8 @@ class MacTool(object):
       dest = os.path.join(base, dest)
 
     args = ['xcrun', 'ibtool', '--errors', '--warnings', '--notices',
-        '--output-format', 'human-readable-text', '--compile', dest, source]
+        '--auto-activate-custom-fonts', '--output-format',

[Nico, 2016/01/26 22:55:11]

do we want this on os x too?

[sdefresne, 2016/01/27 09:24:11]

What is the earliest version of Xcode supporting this flag? Do we still want to
support that version of Xcode with gyp?

+        'human-readable-text', '--compile', dest, source]
     ibtool_section_re = re.compile(r'/\*.*\*/')
     ibtool_re = re.compile(r'.*note:.*is clipping its content')
     ibtoolout = subprocess.Popen(args, stdout=subprocess.PIPE)