Use libjpeg-turbo instead of our own copy of libjpeg.

Check out libjpeg-turbo via DEPS.
Also checkout yasm via DEPS and copy some yasm build files from
Chromium.

BUG=chromium:541704,pdfium:389

Change-Id: Ic7af415f002a3ca2acd9223ed3474dedf3930b32
Reviewed-on: https://pdfium-review.googlesource.com/3470
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/.gitignore b/.gitignore
index c80bf34..289162c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,9 +10,12 @@
 /third_party/freetype/src
 /third_party/icu
 /third_party/instrumented_libraries
+/third_party/libjpeg_turbo
 /third_party/llvm
 /third_party/llvm-build
 /third_party/skia
+/third_party/yasm/binaries
+/third_party/yasm/source/patched-yasm
 /third_party/zlib
 /tools/clang
 /tools/generate_library_loader
@@ -20,13 +23,11 @@
 /tools/memory
 /v8
 /xcodebuild
-Makefile
 .DS_Store
 .gclient
 .gclient_entries
 *.aps
 *.filters
-*.mk
 *.opensdf
 *.pyc
 *.sdf