Add ap_normalize_path() to replace ap_getparents() (with options).

Add ap_normalize_path() to replace ap_getparents() (with options).

include/httpd.h: Declare ap_normalize_path() and flags.
    AP_NORMALIZE_ALLOW_RELATIVE:
        Don't require that the path be absolute as per RFC 7230.
        This is needed for lookup subrequests.
    AP_NORMALIZE_NOT_ABOVE_ROOT:
        Check that directory traversal ("..") don't go above root, or
        initial directory with relative paths.
    AP_NORMALIZE_DECODE_UNRESERVED:
        Decode unreserved characters (like '.') first since they have
        the same semantics encoded and decoded.
    AP_NORMALIZE_MERGE_SLASHES:
        Merge multiple slahes into a single one.
    AP_NORMALIZE_DROP_PARAMETERS:
        Ignore path parameters (";foo=bar"). Not used by httpd but since
        ap_normalize_path() is taken from mod_jk's jk_servlet_normalize()
        it can allow them to use the upstream version now.

server/util.c: Implement ap_normalize_path().

modules/dav/main/util.c: Replace call to ap_getparents() using
    ap_normalize_path() with AP_NORMALIZE_DECODE_UNRESERVED flag since
    the path comes from an obsolute URL (thus potentially %-encoded).

modules/generators/mod_autoindex.c: Replace call to ap_getparents() using
    ap_normalize_path() with AP_NORMALIZE_ALLOW_RELATIVE and
    AP_NORMALIZE_NOT_ABOVE_ROOT flags to be consistent with original code.

include/ap_mmn.h: MINOR bump for ap_normalize_path().

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1879074 13f79535-47bb-0310-9956-ffa450edef68