[Windows] Add support for code signing the final binaries.

The option is controlled with the WITH_WINDOWS_CODESIGN option and needs:

- Signtool must be found on the system, the standard windows sdk folders will be searched for it.
- The path to the pfx file (WINDOWS_CODESIGN_PFX)
- The password for the pfx , this can either be set by the WINDOWS_CODESIGN_PFX_PASSWORD variable but given that ends up in CMakeCache.txt (which might be undesirable) there is a backup option of setting the PFXPASSWORD environment variable on the system.

Reviewers: sergey, juicyfruit

Reviewed By: juicyfruit

Tags: #bf_blender, #platform:_windows

Differential Revision: https://developer.blender.org/D2182

source/blenderplayer/CMakeLists.txt

@@ -58,7 +58,7 @@ if(WIN32 AND NOT UNIX)
 			blenderplayer ${EXETYPE}
 			bad_level_call_stubs/stubs.c
 			${CMAKE_SOURCE_DIR}/release/windows/icons/winblender.rc)
-
+	WINDOWS_SIGN_TARGET(blenderplayer)
 	install(TARGETS blenderplayer
 			COMPONENT Blenderplayer
 			DESTINATION ".")