Vulkan: Enable validation layers on request.

Also adds the build files for the Vulkan layers.

The layers are enabled by default for the tests.

BUG=angleproject:1319

Change-Id: I0b442b36312a1299a932922e1c4e39f00801de49
Reviewed-on: https://chromium-review.googlesource.com/367751
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/.gitignore b/.gitignore
index d48e4df..3ca3f4d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,27 +1,26 @@
-Debug/
-Debug_Win32/
-Debug_x64/
-Debug_ARM/
-Release/
-Release_Win32/
-Release_x64/
-Release_ARM/
-*.sdf
+*.Makefile
 *.ncb
-*.suo
+*.nvuser
+*.opensdf
+*.orig
+*.psess
+*.pyc
+*.rej
+*.sdf
 *.sln
+*.suo
+*.target.mk
+*.TMP
+*.VC.db
+*.VC.opendb
 *.vcxproj
 *.vcxproj.filters
 *.vcxproj.user
-*.VC.opendb
-patches-*
-*.target.mk
-ipch
-debug.txt
-*.opensdf
-*.orig
-*.rej
+*.vsp
+*~
+.gclient
 .gclient_entries
+/src/tests/third_party/gles_conformance_tests
 /testing/gmock
 /testing/gtest
 /third_party/cherry
@@ -33,19 +32,21 @@
 /third_party/spirv-tools-angle/src
 /third_party/vulkan-validation-layers/src
 /third_party/zlib
-/src/tests/third_party/gles_conformance_tests
-out
+angle_internal
+buildtools/
+debug.txt
+Debug/
+Debug_ARM/
+Debug_Win32/
+Debug_x64/
+diag.txt
+ipch
 lib/*
 Makefile
-*.Makefile
-*~
-.gclient
-angle_internal
+out
+patches-*
+Release/
+Release_ARM/
+Release_Win32/
+Release_x64/
 TestResults.qpa
-*.psess
-*.vsp
-*.nvuser
-buildtools/
-*.pyc
-*.TMP
-*.VC.db