Win32:

  install ab.exe
  fix dependency in Apache.dsw (ab is dependent on aprlib and ap)
  fix ab and htdigest projects so that they find all header files
  define ap_signal() in apr.hw - this is o.k. for casual use as with
    cmd-line programs
  use API_VAR_EXPORT as appropriate in getopt.c
general:
  ab doesn't need to declare ap_optarg/ap_optind; fix a warning
  htdigest needs to call ap_initialize() to avoid segfault at
    startup


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85080 13f79535-47bb-0310-9956-ffa450edef68