Upstream fixes to elect Windows static C runtime

[wrowe]

The Windows build of envoy wants to avoid the dependency on MSVCRT.dll, Microsoft's C Runtime, and associated C++ stdlib .dll's.

Most foreign_cc externals support this on a project-by-project basis; a few do not. This issue is tracking the following pull requests to support this feature, and eliminate our .patch files to the CMake logic of these upstream projects.

The following patches are introduced by PR #8280

madler/zlib#448 ENABLE_STATIC_CRT cmake flag
(Open no activity)

nghttp2/nghttp2#1393 ENABLE_STATIC_CRT cmake flag
nghttp2/nghttp2#1394 nghttp2_static.lib/.a output rename
(Accepted and merged for nghttp2 1.40.0 release)

nghttp2/nghttp2#1395 resolve ssize_t
(Patch under discussion)

opentracing/opentracing-cpp@0fb05a4
(Rolled into opentracing-cpp release 1.6.0, needs envoy dependency update)

[wrowe]

libevent/libevent#908
Avoid transforming base C_FLAGS set deliberately

has been submitted, accepted and merged to master. libevent patch will fall off after we pick up a new baseline commit.

[wrowe]

Note we propose to drop these patches from our effective patch set; while they remain useful they are not needed for successful bazel external_cmake() builds;
madler/zlib#448 ENABLE_STATIC_CRT cmake flag
nghttp2/nghttp2#1393 ENABLE_STATIC_CRT cmake flag
nghttp2/nghttp2#1394 nghttp2_static.lib/.a output rename

[wrowe]

#8280 passes all tests using Envoy's bazel cflag elections without the individual proposals upstream to add this toggle for their Debug/Release/ReleaseWithDebInfo targets, so we can safely close this ticket as not blocking envoy binaries.