Funnel fetching and building LLVM instructions into GettingStarted.

Modernize the build steps a little.

Remove comments saying CMAKE_BUILD_TYPE defaults to Debug as that's not true anymore (must explicitly pass it).

Reviewed By: MaskRay, hans

Differential Revision: https://reviews.llvm.org/D145413

Fixed whitespace and punctuation issues, added a name to a link, and
fixed a typo.

We are moving away from building the runtimes with LLVM_ENABLE_PROJECTS,
however the documentation was largely outdated. This commit updates all
the documentation I could find to use LLVM_ENABLE_RUNTIMES instead of
LLVM_ENABLE_PROJECTS for building runtimes.

Note that in the near future, libcxx, libcxxabi and libunwind will stop
supporting being built with LLVM_ENABLE_PROJECTS altogether. I don't know
what the plans are for other runtimes like libc, openmp and compiler-rt,
so I didn't make any changes to the documentation that would imply
something for those projects.

Once this lands, I will also cherry-pick this on the release/14.x branch
to make sure that LLVM's documentation is up-to-date and reflects what
we intend to support in the future.

Differential Revision: https://reviews.llvm.org/D119351

Differential Revision: https://reviews.llvm.org/D119279

Differential Revision: https://reviews.llvm.org/D112265

This commit primarily checks that my newly acquired commit access works.
But this is also a real spelling fix.

The updated list is based on the output of
cmake -G Ninja -S llvm -B build -DLLVM_ENABLE_PROJECTS='foo'.

Differential Revision: https://reviews.llvm.org/D110124

Discussion thread:
https://lists.llvm.org/pipermail/llvm-dev/2021-January/148048.html

Move debuginfo-test into a subdirectory of a new top-level directory,
called cross-project-tests. The new name replaces "debuginfo-test" as an
LLVM project enabled via LLVM_ENABLE_PROJECTS.

Differential Revision: https://reviews.llvm.org/D95339

Reviewed by: aprantl

Now that llvm's minimum version is 3.13.4 anyway and `-S` is
introduced in the same version[1], let's use this little
time saving option to simplify the build instructions.

[1]: https://cgold.readthedocs.io/en/latest/glossary/-S.html



Authored-By: Ebrahim Byagowi <ebrahim@gnu.org>

Differential-Revision: https://reviews.llvm.org/D95049

This reverts commit cbe0ee1a.

This reverts commit 9d54b166.

This reverts commit ab31797e.

Also, some spelling fixes.  Test commit.

As discussed on llvm-dev [1], this patch adds a brief CONTRIBUTING.md to
the top-level of the repo, with a pointer to Contributing.html. This
should make it easier to discover the contributing information and also
be highlighted in the Github UI.

It also updates README.md to link to Contributing.html.

[1] http://lists.llvm.org/pipermail/llvm-dev/2019-November/137141.html

Reviewers: tonic, rnk, jhenderson, meikeb

Reviewed By: rnk, jhenderson, meikeb

Differential Revision: https://reviews.llvm.org/D70743

Reviewed and approved by chandlerc.

As GitHub is the canonical LLVM repository now, embrace GitHub's way of displaying basic build instructions in the top-level readme.md.

Per llvm.org: "The name "LLVM" itself is not an acronym; it is the full
name of the project."

llvm-svn: 344766

monorepo.

llvm-svn: 316185