GDI: portability fix

[Hans Leidekker]

MinGW has a unistd.h header but it doesn't have pipe() nor fork().
This patch adds configure checks for these functions. With this
patch our GDI dll builds on MinGW.

Changelog:
  Add configure check for pipe() and fork().
  Use the check to fix the MinGW build.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: gdi_printdrv_c.diff
Type: text/x-diff
Size: 1137 bytes
Desc: not available
Url : http://www.winehq.org/pipermail/wine-patches/attachments/20041011/1fcf84a6/gdi_printdrv_c.bin