Merge branch 'bc/drop-ancient-libcurl-and-perl'

Merge branch 'bc/drop-ancient-libcurl-and-perl'

Drop support for older libcURL and Perl.

* bc/drop-ancient-libcurl-and-perl:
  gitweb: make use of s///r
  Require Perl 5.26.0
  INSTALL: document requirement for libcurl 7.61.0
  git-curl-compat: remove check for curl 7.56.0
  git-curl-compat: remove check for curl 7.53.0
  git-curl-compat: remove check for curl 7.52.0
  git-curl-compat: remove check for curl 7.44.0
  git-curl-compat: remove check for curl 7.43.0
  git-curl-compat: remove check for curl 7.39.0
  git-curl-compat: remove check for curl 7.34.0
  git-curl-compat: remove check for curl 7.25.0
  git-curl-compat: remove check for curl 7.21.5