Merge r1462219,1462224:

    apr_uri_parse(): Do not accept invalid characters in the scheme.
    Per RFC 3986 3.3, enforce that the first segment of a relative path does
    not contain a colon.
    
    PR: 52479


git-svn-id: https://svn.apache.org/repos/asf/apr/apr-util/branches/1.5.x@1462434 13f79535-47bb-0310-9956-ffa450edef68