Merge pull request #897 from Vsevolod-Livinskij/knc_header_fix

Knc header fix
Merge pull request #899 from ncos/knc-backend-merge

Added several i8/i16 functions to knc.h
__smear_i8/16 was added
__not_equal_i8/16 was added
Minor fixes to remove copy-paste
Merge commit
LLVM trunk build fail fix (MDNode interface change)
insert/extract_element_i8/16 and broadcast_i8/16
__reduce_add/min/max_int64
cast double/float to/from int64
Disable optimization to eliminate illegal results
Fix for __cast_uitofp
Merge pull request #901 from ncos/ispc_build_fails

LLVM trunk build fail fix (MDNode interface change)
Merge pull request #902 from Vsevolod-Livinskij/knc_header_fix

Knc header fix
Merge pull request #904 from jbrodman/master

Disable optimization to eliminate illegal results
Merge branch 'master' of https://github.com/ncos/ispc into knc-backend-merge

Conflicts:
	examples/intrinsics/knc.h