This reduces the number of moving parts in ABI compatibility checks.
Additionally, it also allows to use OpenSSL in FIPS mode while still
using md5 for non-security tasks.

    *) Change: now the ngx_http_charset_module works for subrequests, if
       the response has no "Content-Type" header line.

    *) Bugfix: if the "proxy_pass" directive has no URI part, then the
       "proxy_redirect default" directive add the unnecessary slash in
       start of the rewritten redirect.

    *) Bugfix: the internal redirect always transform client's HTTP method
       to GET, now the transformation is made for the "X-Accel-Redirect"
       redirects only and if the method is not HEAD; the bug had appeared
       in 0.3.42.

    *) Bugfix: the ngx_http_perl_module could not be built, if the perl was
       built with the threads support; the bug had appeared in 0.3.46.

    *) Feature: the ngx_http_perl_module.

    *) Change: the "valid_referers" directive allows the referreres without
       URI part.