Support for building bf-blender under windows with gcc (huge thanks to

Florian Eggenburger).

Full instructions are in doc/README.windows-gcc.

Main differences from Florian's patch:

- the 'lib' dir should now be the same level as the 'blender' dir (rather
than being a subdir of 'blender'). This is consistent with the other
platforms that bf-blender supports (tuhopuu will also adopt this convention
hopefully soon).

- the script 'free_windows-env.mk' is no longer needed ... see the
docs about how this is overcome (again, tuhopuu will hopefully
also follow this route soon).

- the dlltool dir has it's own Makefile that builds all of the
needed stub libraries from the dll's in cvs.

source/blender/render/intern/source/initrender.c

@@ -1260,7 +1260,7 @@ void RE_animrender(struct View3D *ogl_render_view3d)
 	} else if (R.r.imtype==R_MOVIE) {
 		start_movie();
 #endif
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(FREE_WINDOWS)
 	} else if (R.r.imtype == R_AVICODEC) {
 		start_avi_codec();
 #endif
@@ -1290,7 +1290,7 @@ void RE_animrender(struct View3D *ogl_render_view3d)
 			} else if (R.r.imtype == R_MOVIE) {
 				append_movie((G.scene->r.cfra));
 #endif
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(FREE_WINDOWS)
 			} else if (R.r.imtype == R_AVICODEC) {
 				append_avi_codec((G.scene->r.cfra));
 #endif
@@ -1330,7 +1330,7 @@ void RE_animrender(struct View3D *ogl_render_view3d)
 	} else if (R.r.imtype==R_MOVIE) {
 		end_movie();
 #endif
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(FREE_WINDOWS)
 	} else if (R.r.imtype == R_AVICODEC) {
 		end_avi_codec();
 #endif