GN Windows build fixes

third_party/libusb/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 config("libusb_config") {
   include_dirs = [
     "src/libusb",
   ]
 }
 
@@ skipping 73 matching lines @@
   } else {
     sources -= [
       "src/libusb/os/linux_udev.c",
       "src/libusb/os/linux_usbfs.c",
       "src/libusb/os/linux_usbfs.h",
     ]
   }
 
   if (is_win) {
     include_dirs += [ "src/msvc" ]
+    sources -= [
+      "src/libusb/os/poll_posix.c",

[scottmg, 2014/04/11 21:43:26]

why aren't these filtered by the set_assignment_filter?

[brettw, 2014/04/11 23:05:00]

They're .c files. The filter only has .cc in it now. I'm not excited about
making the patterns more complicated and I don't think this will come up that
often.

[scottmg, 2014/04/11 23:12:31]

Ah, missed that. Makes sense I guess, but I feel like people will probably get
bitten now and then.

+      "src/libusb/os/threads_posix.c",
+    ]
   } else {
     include_dirs += [ "src" ]
     sources -= [
       "src/libusb/os/poll_windows.c",
       "src/libusb/os/poll_windows.h",
       "src/libusb/os/threads_windows.c",
       "src/libusb/os/threads_windows.h",
       "src/libusb/os/windows_common.h",
       "src/libusb/os/windows_usb.c",
       "src/libusb/os/windows_usb.h",
       "src/msvc/config.h",
       "src/msvc/inttypes.h",
       "src/msvc/stdint.h",
     ]
   }
 }