added avx2-i64x4 and avx1.1-i64x4 targets

Added two new targets:

  * avx1.1-i64x4
  * avx2-i64x4

No fails on both targets, e.g.:

    ./run_tests.py --target=avx2-i64x4

    Using test compiler: Intel(r) SPMD Program Compiler (ispc), 1.5.1dev (build commit ba4977cd84ccc135 @ 20131015, LLVM 3.3)
    Using C/C++ compiler: clang version 3.3 (tags/RELEASE_33/final 192676)

    Running 8 jobs in parallel. Running 1206 tests.
     Done 1206 / 1206 [./tests_errors/void-qualifiers-3.ispc]                
    No fails
    No new fails