Summary:
TSAN builds for gcc 4.9 need a PIC version of the libraries
taken from the fbcode platform. This is accomplished by assuming every
.a has a _pic.a sibling, and by fixing the third-party2 zlib build.
Test Plan: make COMPILE_WITH_TSAN=1 check
Reviewers: sdong, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D50331
c745f1d2c4