[llvm-dev] (Thin)LTO llvm build

[Carsten Mattner via llvm-dev]

After figuring out the fault in the configuration step and rebuilding,
and then rebuilding again by forcing it with `ninja -k 16`, I managed to
build everything but 12 ninja targets.

I have to sift through them before I can report more, and I don't
don't know if it's small enough to post here, but some of the more
interesting errors are:

llvm/projects/compiler-rt/lib/tsan/dd/dd_interceptors.cc:226:20:
error: redefinition of 'realpath'
INTERCEPTOR(char*, realpath, const char *path, char *resolved_path) {
                   ^
/usr/include/bits/stdlib.h:37:8: note: previous definition is here
__NTH (realpath (const char *__restrict __name, char *__restrict __resolved))

[...]

libomp.so
duplicate symbol __kmp_get_reduce_method in version script
duplicate symbol __kmp_itt_fini_ittlib in version script
duplicate symbol __kmp_itt_init_ittlib in version script
LLVM ERROR: A @@ version cannot be undefined