Include configurable multilib support in llvm-project.patch

This commit adds the following multilib patches to our downstream
patch against llvm-project, which form a series adding support for a
set of multilib configurations specified at run time via a YAML
configuration file instead of built into the clang binary:

 - D142893 (as committed in 850dab0f2537bb31103578fc35caef2f1ad98f04)
 - D142905 (diff 506044, uncommitted as of 2023-03-20)
 - D142932 (diff 505283, uncommitted as of 2023-03-20)
 - D142933 (diff 505643, uncommitted as of 2023-03-20)
 - D142986 (diff 505644, uncommitted as of 2023-03-20)
 - D143059 (diff 505288, uncommitted as of 2023-03-20)
 - D143075 (diff 505290, uncommitted as of 2023-03-20)
 - D143587 (diff 505451, uncommitted as of 2023-03-20)

Those patches didn't apply cleanly against LLVM 16; some merge
conflicts (syntactic and semantic) have been fixed.

Also, I've changed the expected value of the 'MultilibVersion' tag
from 1.0 to 0.1. The value in the above LLVM patches reflects the
version number intended to be current when those patches land on LLVM
main. But the patches haven't passed review yet, so there's a
possibility that changes will be made before they do, and therefore
the version committed here might not match 1.0 in every detail.

Additionally, this commit includes the following three test fix
patches, which did apply cleanly:

 - D143590 (as committed in f28c28e6645723c01c73478a9d18f0bf0551767a)
 - D143666 (as committed in d61a863050bb4afd22d08bbe53af1e24c0657aba)
 - D144542 (as committed in 67e28a3010e1852ec670cf5346fd171bf2a16774)

Author: statham-arm