Copy stable/11@r303970 to releng/11.0 as part of the 11.0-RELEASE
cycle.

Prune svn:mergeinfo from the new branch, and rename it to RC1.

Update __FreeBSD_version.

Use the quarterly branch for the default FreeBSD.conf pkg(8) repo and
the dvd1.iso packages population.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Merge LLVM libunwind fixes

r302475: libunwind: limit stack usage in unwind cursor

This may be reworked upstream but in the interim should address the
stack usage issue reported in the PR.

r303061: libunwind: Properly align _Unwind_Exception.

_Unwind_Exception is required to be double word aligned. GCC has
interpreted this to mean "use the maximum useful alignment for the
target" so follow that lead.

PR: 206384 (r302475)
Obtained from: LLVM review D22543 (r303061)
Approved by: re (gjb)

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Merge LLVM libunwind revision 256779

Bring LLVM libunwind snapshot into contrib/llvm/projects

Import LLVM libunwind snapshot revision 246528

From https://llvm.org/svn/llvm-project/libunwind/trunk/