backport from 2.1:

Prevent endless loops of internal redirects in mod_rewrite by
aborting after exceeding a limit of internal redirects. The
limit defaults to 10 and can be changed using the RewriteOptions
directive with the new MaxRedirects=n argument.
(The latter required some restructuring of the RewriteOptions
 evaluation code).

PR: 17462
Reviewed by: Will Rowe, Ian Holsman


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99021 13f79535-47bb-0310-9956-ffa450edef68