Cleanup in fixup.h

Summary: * Renames public fields m_foo to foo.

* Uses C++11 member initialization.

Reviewed By: @edwinsmith

Differential Revision: D1497114
Fix `cmake verification` build step

Summary: On the HHVM CI systems, the CMake/ folder
is in a slightly different spot than in the public repo.

Reviewed By: @fredemmott

Differential Revision: D1523762