Implement cygw32

Here, we use the generic window-system configuration system we just
implemented to support the w32 window-system in the mainline build
under Cygwin.  (Previously, the w32 window system could only be
compiled as part of the NT-native Emacs build process.)

The changes in this patch need to be applied atomically in order to
avoid breaking Emacs.  The changes include:

  - Changes throughout the Lisp and C code to not assume that
      NT Emacs and the w32 window system are synonymous.

  - Wiring up the regular select(2) event loop to Windows messages

  - Cleaning up the w32 drag-and-drop receiving code.

  - Exposing Cygwin path conversion functions to elisp.

  - Unicode file dialog support when compiling for Cygwin.

  - Splitting the w32 term lisp initialization code into code
    applicable to any w32 window-system and code specific to
    system-type windows-nt.

  - Integrating the old and new w32 code into the build system.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/unexw32.c b/src/unexw32.c
index 52b2ec4bf2b..8061227d3a8 100644
--- a/src/unexw32.c
+++ b/src/unexw32.c
@@ -83,7 +83,7 @@ DWORD  extra_bss_size_static = 0;
 PIMAGE_SECTION_HEADER heap_section;
 
 #ifdef HAVE_NTGUI
-HINSTANCE hinst = NULL;
+extern HINSTANCE hinst;
 HINSTANCE hprevinst = NULL;
 LPSTR lpCmdLine = "";
 int nCmdShow = 0;