Variable for path to SDK root

[Jann Röder]

Hi,
it appears that in order to build gpg using Xcode 5 correctly we need to
specify the absolute path to stdint.h in the portfile. On my system the
files is at
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/stdint.h

I was wondering if there is a variable that points to the SDK Root
"/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/"
on any version of OS X / XCode.

Background:

The current version of the gpg2 port has this line in it:

configure.env   gl_cv_absolute_stdint_h=/usr/include/stdint.h

However with XCode 5 the file at this location doesn't exist. It needs to be

configure.env
gl_cv_absolute_stdint_h=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/stdint.h

instead.

Thanks,
Jann