Bug 1523198 - Make DIA_SDK_PATH a normal configure input. r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D17785

--HG--
extra : moz-landing-system : lando

build/moz.configure/windows.configure

@@ -277,14 +277,17 @@ def vc_path(c_compiler, toolchain_search_path):
     return os.path.normpath(result)
 
 
-@depends(vc_path)
+option(env='DIA_SDK_PATH', nargs=1,
+       help='Path to the Debug Interface Access SDK')
+
+
+@depends(vc_path, 'DIA_SDK_PATH')
 @checking('for the Debug Interface Access SDK', lambda x: x or 'not found')
 @imports('os')
 @imports(_from='os.path', _import='isdir')
-def dia_sdk_dir(vc_path):
-    dia_sdk_dir_env = os.environ.get('DIA_SDK_PATH')
-    if dia_sdk_dir_env:
-        return os.path.normpath(dia_sdk_dir_env)
+def dia_sdk_dir(vc_path, dia_sdk_path):
+    if dia_sdk_path:
+        return os.path.normpath(dia_sdk_path[0])
 
     if vc_path:
         # This would be easier if we had the installationPath that