Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/1caf3a6..b19d8a0

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Change-Id: I1816fe20864835c2615f09f11666165b0776cf9e
Reviewed-on: https://chromium-review.googlesource.com/511743Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45471}

DEPS

@@ -8,7 +8,7 @@ vars = {
 
 deps = {
   "v8/build":
-    Var("chromium_url") + "/chromium/src/build.git" + "@" + "1caf3a69f3b0379c9fef2493aa1b3cda96e17d7b",
+    Var("chromium_url") + "/chromium/src/build.git" + "@" + "b19d8a0c0ee0fb00c6982a7a3714efda621e94cc",
   "v8/tools/gyp":
     Var("chromium_url") + "/external/gyp.git" + "@" + "eb296f67da078ec01f5e3a9ea9cdc6d26d680161",
   "v8/third_party/icu":