John's revert of my removal commit dragged back a bunch of cygwin/sunos
cruft, as well as re-adding RegExp.cpp to the host libshared, that we don't
need.
Instead, remove this and add libgnuregex_build to just the tools/keymap
link alongside the FreeBSD gnuregex case.
It was needed on macOS for a time when BUrl used regexes for parsing.
Now it does not, and so we can remove libshared's RegExp from build
libshared, and thus also libgnuregex.
Cygwin and Solaris rely on Haiku supplying a glibc-compatible regex.h header.
Before r38031, Solaris was able to reuse cygwin/regex.h successfully. Import
the latest stable 2.11 posix/regex.h to avoid local trickery and to silence
some RE_* errors.
It is very likely necessary to update cygwin/regex.h as well, but I don't have
a test setup to verify.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@38096 a95241bf-73f2-0310-859d-f6bbb57e9c96
