Roll android_ndk, build, buildtools.

Roll DEPS for android_ndk to e951c37287c7d8cd915bf8d4149fd4a06d808b55.
https://chromium.googlesource.com/android_ndk/+log/d5752321..e951c372

Roll DEPS for build to b1bf4b84cb5db309fda657ebd19a6c3d2ebdcb66.
https://chromium.googlesource.com/chromium/src/build/+log/097c79ba..b1bf4b84

Roll DEPS for buildtools to f115f4786771afdfacb18a2299541b23e21f4792.
https://chromium.googlesource.com/chromium/buildtools/+log/b36c7b60..f115f478

The android_ndk version needs to be updated to r16.

android_ndk and build cannot be rolled separately. build depends on the
buildtools changes.

This enables pdfium to be built with emscripten.

Bug: chromium:804907
Change-Id: If442e92f2f608ae20b476b9b077111e2596187cf
Reviewed-on: https://pdfium-review.googlesource.com/24890
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
diff --git a/DEPS b/DEPS
index 52d11da..8c70d4c 100644
--- a/DEPS
+++ b/DEPS
@@ -13,10 +13,10 @@
   'chromium_git': 'https://chromium.googlesource.com',
   'pdfium_git': 'https://pdfium.googlesource.com',
 
-  'android_ndk_revision': 'd57523210239b867fa4fb9d05c2aacc3f1802fe0',
+  'android_ndk_revision': 'e951c37287c7d8cd915bf8d4149fd4a06d808b55',
   'binutils_revision': 'e146228c20af6af922887d0be2d3641cbffb33c5',
-  'build_revision': '097c79babc9b2ce40b61c3e33da1c6681acf837c',
-  'buildtools_revision': 'b36c7b60ed73919b157c7d23ec5fce2aa69ab05e',
+  'build_revision': 'b1bf4b84cb5db309fda657ebd19a6c3d2ebdcb66',
+  'buildtools_revision': 'f115f4786771afdfacb18a2299541b23e21f4792',
   'catapult_revision': 'd624b3ced2c81d4fb4ea98a8dbb4532272cc1e0a',
   'clang_revision': 'ac1e5f78c39dc2a262af149404dd36c140eecdc1',
   'cygwin_revision': 'c89e446b273697fadf3a10ff1007a97c0b7de6df',