Summary:
On unix platforms, check to see if the compiler supports the `-faligned-new`
and `-Wno-noexcept-type` flags before adding them to the compiler command line
flags.

Reviewed By: yfeldblum

Differential Revision: D6787808

fbshipit-source-id: d34af5ae4251ad3639fdaa1a8d5cb2df4b10e986