(ITS#8273) file:// URLs broken on Windows

[hyc@openldap.org]

Full_Name: Howard Chu
Version: 2.4
OS: Win32
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (78.155.231.14)
Submitted by: hyc


file URLs with absolute paths are parsed incorrectly on Windows. The current
code expects an absolute path in Unix form:
  file:///etc/ldap.conf

In our test suites we just concatenate "file://" with an absolute path.

On Windowsn ababsolute path starts with a drive letter and a colon, so our test
suite doing simple concatenation uses
  file://C:/some/thing

This is actually invalid; the proper form would be
  file:///C:/some/thing

but the current parser won't do the right thing for either form.

It MUST be fixed to accept the latter form with 3 slashes. I'm inclined to also
accept the form with 2 slashes, to avoid hacking up our test suite to handle
this case.