Reset enviroment for math_tests

Bug: 17390824
Change-Id: I42f4c8d9199a2efe7641f0b0e64580cacb5695da
Add needed headers
Revert "Disable Clang..." && "Added a bionic systrace class..."

This reverts commit 356a6249d8072f6cc8038d9939f360c08c583d49.