Change to Clang/LLVM ToT(Top of the Tree)

Change to Clang/LLVM ToT(Top of the Tree)

Two minor changed in this patch

1.files that use llvm new api.
backend/src/llvm/llvm_{gen_backend,passes}.cpp

2.change backend IR from ptx32 to nvptx.
all test cases in utest passed [SUSSECC], but may give wrong output.
for example, app_mandelbrot makes a wrong picture.
silk's cl_gl_fill passed.

revision of Clang/LLVM components:
llvm r168773
clang r168774
compiler-rt r168700

Signed-off-by: Feng, Boqun <boqun.feng@intel.com>
Reviewed-by: Zhigang Gong <zhigang.gong>