Bug 1416052 - Move export of FOUND_MOZCONFIG to Python; r=nalexander

This should have the same net result.

TBH, I'm not 100% convinced we need this export. It is only needed
to send variables to sub-makes. And the only make file reading
FOUND_MOZCONFIG is client.mk. Since the code that evals the
auto-generated make file is always executed in client.mk, we
shouldn't need this export.

All this code is going away soon anyway. So I'm inclined to cargo
cult this just in case.

MozReview-Commit-ID: DqF1BU702A

--HG--
extra : rebase_source : 31859c0d4bb6ceb06367bf0ca554d79d57d2d0c3

client.mk

@@ -52,8 +52,6 @@ endef
 MOZCONFIG_CONTENT := $(subst ||,$(CR),$(subst || ,$(CR),$(shell cat $(OBJDIR)/.mozconfig-client-mk | sed 's/$$/||/')))
 include $(OBJDIR)/.mozconfig-client-mk
 
-export FOUND_MOZCONFIG
-
 # As '||' was used as a newline separator, it means it's not occurring in
 # lines themselves. It can thus safely be used to replaces normal spaces,
 # to then replace newlines with normal spaces. This allows to get a list

python/mozbuild/mozbuild/controller/building.py

@@ -1339,6 +1339,7 @@ class BuildDriver(MozbuildObject):
             if mozconfig['path']:
                 fh.write(b'FOUND_MOZCONFIG=%s\n' %
                          mozpath.normsep(mozconfig['path']))
+                fh.write(b'export FOUND_MOZCONFIG\n')
 
         append_env['OBJDIR'] = mozpath.normsep(self.topobjdir)