Merge branch 'ps/build-meson-fixes-0130'

Assorted fixes and improvements to the build procedure based on
meson.

* ps/build-meson-fixes-0130:
  gitlab-ci: restrict maximum number of link jobs on Windows
  meson: consistently use custom program paths to resolve programs
  meson: fix overwritten `git` variable
  meson: prevent finding sed(1) in a loop
  meson: improve handling of `sane_tool_path` option
  meson: improve PATH handling
  meson: drop separate version library
  meson: stop linking libcurl into all executables
  meson: introduce `libgit_curl` dependency
  meson: simplify use of the common-main library
  meson: inline the static 'git' library
  meson: fix OpenSSL fallback when not explicitly required
  meson: fix exec path with enabled runtime prefix