Intrin.h: include setjmp.h to get a jmp_buf definition

This makes sure that the ms-intrin.cpp test passes by providing
a mock setjmp.h as a test input.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@200344 91177308-0d34-0410-b5e6-96231b3b80d8