adding --extra option and correction pathes to ispc compiler
Merge pull request #623 from ifilippov/testing

adding --extra option and correction pathes to ispc compiler
patch for LLVM for fails at avx-x2
Merge pull request #624 from ifilippov/fix1

patch for LLVM for fails on avx-x2 target
fix for ISPC for compfails at sse4-i8 and sse4-i16
Merge pull request #626 from ifilippov/fix1

fix for ISPC for compfails at sse4-i8 and sse4-i16
Switching default compiler on Unix from g++ to clang++
Switch examples on Unix from using g++ to clang++
Fix problem with building ISPC by clang 3.4
Enable clang as default C++ compiler used by run_tests.py and perf.py
fail_db.txt update with fails with clang 3.3 as a C++ compiler for tests (Linux)
Update fail_db with new passes after change in trunk
Merge pull request #627 from dbabokin/clang_build

Switch over to clang as default C++ compiler for build and test
Fail_db update on Mac with clang 3.3 compiler
Merge pull request #628 from dbabokin/fail_db

Fail_db update on Mac with clang 3.3 compiler
Fix small typo for NEON targets in Target::SupportedTargets
Merge pull request #629 from mmp/typo

Fix small typo for NEON targets in Target::SupportedTargets
new changes in test system
Merge pull request #630 from ifilippov/testing

new changes in test system
 added avx2-i64x4 and avx1.1-i64x4 targets