[gtk-osx] Set SDKROOT=SDKDIR for CMake.

[John Ralls <jralls src gnome org>]

commit be6dbcd00636bf28355c5ce1dcdeec95c87839ef
Author: John Ralls <jralls ceridwen us>
Date:   Fri Oct 9 10:04:15 2015 -0700

    Set SDKROOT=SDKDIR for CMake.

 jhbuildrc-gtk-osx |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/jhbuildrc-gtk-osx b/jhbuildrc-gtk-osx
index fe182d2..c729ec0 100644
--- a/jhbuildrc-gtk-osx
+++ b/jhbuildrc-gtk-osx
@@ -262,6 +262,7 @@ def setup_sdk(target, sdk_version, architectures=[_default_arch]):
         #developing, and it takes a lot of typing, so define a
         #convenience environment variable:
         environ_append('SDKDIR', sdkdir)
+        environ_append('SDKROOT', sdkdir)
 
 #Apple Documentation says that "-syslibroot" is the arg to pass to the
 #linker, but we are using the compiler to control the linker, and