Collaborative work: (Thanks, dreid!)

Implement OID checking for mod_ssl. This code allows for checking of arbitrary client
certificate extensions by OID, in a syntax like:
   SSLRequire "BaDCA Generated Certificate" in Oid("2.16.840.1.113730.1.13") \
          || "committers"                   in Oid("1.3.6.1.4.1.18060.1")
Note the following:
* A given OID can occur multiple times in one cert, with different values. Therefore
  the OID function compares the left-hand string against each of the OID values,
  until a complete match is found. If none patches, the result is FALSE
* The left hand side can be another expression, so can be a reference to a variable
  or an file() invocation etc.
* The OID is also just a reference to a string, or function, or whatever.
* My manual description is very short. Someone else please help improve the description



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@219940 13f79535-47bb-0310-9956-ffa450edef68