Autoconf doesn't remake configure if creation time on configure.in
is older than the previous version.

This caused problems on windows so always recreate configure when
running ./otp_build autoconf

In options `plain` and `smp`, code checking for option being `opt` had
been dead since R12B-5.

* binarin/fix-build-tool-paths/PR-1023/OTP-13562:
  Fix program paths used in build process

Conflicts:
	erts/configure.in

Not every OS has '/bin/rm' or '/bin/pwd' at exactly that location.

In some places in configure scripts result of AC_PATH_PROG was already
correctly used, this patch makes this usage more consistent.

As for `/bin/pwd` in `otp_build`, shell built-in one is already used in
mingw parts - so it should cause no harm to use it everywhere.
Difference is only in symlinks resolution - non-builtin `pwd` always
returns absolute path, and builtin-one could take into account what
sequence of user actions lead to current value of $PWD.

The test_server application has previously been deprecated.

In OTP 19, we will move relevant parts of test_server into the
common_test application. Test suites that include test_server.hrl
must be updated to include ct.hrl instead. Test suites that include
test_server_line.hrl must removed that inclusion. Test suites that
call the test_server module directly will continue to work in OTP 19.

The test suites for Erlang/OTP are built and executed in exactly
the same way as previously.

Here are some more details.

The modules test_server*.erl and erl2html2.erl in lib/test_server/src
have been moved to common_test/src.

The test_server.hrl and test_server_line.hrl include files have
been deleted. The macros in test_server.hrl have been copied into
lib/common_test/include/ct.hrl.

The ts*.erl modules and their associated data files in
lib/test_server/src has been been moved to the new directory
lib/common_test/test_server. The ts* modules are no longer built
to lib/common_test/ebin. They will only built when 'make release_tests'
is executed.

The test suite for test_server has been moved to lib/common_test/test.

The rest of the files have been deleted.

Allow building win32 on MSYS2.
Avoid msys2 path conversion which does not work.
And print the real windows command when something fails.

Distribute aclocal.m4, install-sh, config.guess, and config.sub
to applications at build time instead of having multiple identical
copies committed in the repository.