[cairo] Problems with gl surface backend on W32

[LRN]

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Aside from the fact that it just doesn't compile OOTB with mingw+glew
(had make a few quick'n'dirty compatibility hacks (patches are
attached)), i've also found some strange things with calling
convention mismatch. A patch for that is attached separately.

That patch fixed immediate problem with wglGetProcAddress, but,
apparently, all functions that are loaded by that function also use
stdcall, and thus must be called appropriately, and their CC must be
known at compilation time.
I have no idea how to fix things on such a scale.
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--- cairo-1.12.14/src/cairo-wgl-context.c.orig	2013-04-03 23:15:02 +0400
+++ cairo-1.12.14/src/cairo-wgl-context.c	2013-04-03 23:05:40 +0400
@@ -173,6 +173,16 @@
     return CAIRO_STATUS_SUCCESS;
 }
 
+/* This wrapper function has cdecl convention, just like all other
+ * get_proc_addr() variants.
+ * It calls wglGetProcAddress(), which uses stdcall convention.
+ */
+static cdecl void *
+cairo_cdecl_wglGetProcAddress (const char *procname)
+{
+  return wglGetProcAddress (procname);
+}
+
 cairo_device_t *
 cairo_wgl_device_create (HGLRC rc)
 {
@@ -200,7 +210,7 @@
     ctx->base.destroy = _wgl_destroy;
 
     status = _cairo_gl_dispatch_init (&ctx->base.dispatch,
-				      (cairo_gl_get_proc_addr_func_t) wglGetProcAddress);
+				      (cairo_gl_get_proc_addr_func_t) cairo_cdecl_wglGetProcAddress);
     if (unlikely (status)) {
 	free (ctx);
 	return _cairo_gl_context_create_in_error (status);