[test-suite] Add GCC C Torture Suite

Summary:
This patch adds support for testing clang/LLVM against the GCC Torture
suite.

This patch adds the CMake configuration and licence information for these tests. A follow-up patch will add the testcases themselves (which are too large to review, and included without modifications). They will be committed together.

Reviewers: hfinkel, kristof.beyls, asb

Reviewed By: kristof.beyls

Subscribers: khcheang, mehdi_amini, jvesely, krytarowski, fedor.sergeev, zzheng, steven_wu, dexonsmith, arphaman, jfb, mstorsjo, lewis-revill, simoncook, s.egerton, riccibruno, asb, mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66887

git-svn-id: https://llvm.org/svn/llvm-project/test-suite/trunk@374155 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed