This PR changes the build system to use use the sources for the module
`omp_lib` and the `omp_lib.h` include file from the `openmp` runtime
project and not from a separate copy of these files. This will greatly
reduce potential for inconsistencies when adding features to the OpenMP
runtime implementation.
When the OpenMP subproject is not configured, this PR also disables the
corresponding LIT tests with a "REQUIRES" directive at the beginning of
the OpenMP test files.
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Co-authored-by: Valentin Clement (バレンタイン クレメン) <clementval@gmail.com>
Any header or module file in the Flang source directory is of no use to
the compiler unless it is copied into the build directory. Indeed, all
compiler search paths are relative to the compiler executable (flang-new
in our case). Hence, "omp_lib.h" should be copied into the build
directory alongside other compiler-provided files that can be "included"
(header files) or "used" (module files).
For now, "omp_lib.h" is copied into "<build-dir>/include/flang/OpenMP".
We may decide to change this in future. For example, Clang copies a
bunch of runtime headers into “<build-dir>/lib/clang/<version-number>”.
We could also consider using a similar header from a different
sub-project.
Flang's driver search path is updated accordingly. A rule for
"installing" the "omp_lib.h" header is _yet to be added_ (we will also
need to determine the suitable location for this).
Differential Revision: https://reviews.llvm.org/D122015
