Create per-uid GCOV_PREFIX dir in the getenv wrapper

Bug: http://b/116873221

With https://reviews.llvm.org/D65245, the profile runtime assumes that
the directory ${GCOV_PREFIX} is already created.  Before returning from
the getenv wrapper, create the per-uid ${GCOV_PREFIX}.

Test: cuttlefish builds and boots with new Clang.
Change-Id: I276e1a92b3cb18ee85bb4451159b131d8ebca4a2
1 file changed