[PATCH] strptime

I haven't followed the discussion on strptime for Windows, but I'm wondering
why we are using it for non-Windows builds now. Shouldn't we either check
whether it is already available or not, #ifdef WIN32, or definitely use the
glibc function on Linux?! (And shouldn't it be in src/af/util/win?)

Could someone please check whether the attached patch is ok for Windows?

And BTW, there seem to be issues with the implementation:

  ut_strptime.c:428: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:475: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:500: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:589: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:621: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:636: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:642: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:648: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:658: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:783: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:803: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:808: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:814: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:820: warning: comparison of unsigned expression < 0 is always false
  ut_strptime.c:826: warning: comparison of unsigned expression < 0 is always false

Ingo