[build] Fix V8 deps for qemu

This ports https://crrev.com/c/1185020
[Fuchsia] Add Mac build support.

This also rolls v8/build:
https://chromium.googlesource.com/chromium/src/build/+log/9f16b23..ed29828

TBR=yangguo@chromium.org

Bug: chromium:707030
Change-Id: Ib74df070fa4a2b77c4837f82e4e4d8666a3166e5
Reviewed-on: https://chromium-review.googlesource.com/1199404
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55555}

DEPS

@@ -13,7 +13,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '9f16b23637d2f9256e332a9a7e82143f46419991',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'ed298283623e9ded41078d45d674cae8e7b49a46',
   'v8/tools/gyp':
     Var('chromium_url') + '/external/gyp.git' + '@' + 'd61a9397e668fa9843c4aa7da9e79460fe590bfb',
   'v8/third_party/depot_tools':
@@ -62,14 +62,14 @@ deps = {
     Var('chromium_url') + '/external/github.com/tc39/test262.git' + '@' + '835c85c26e35afbac872d4a98ad66585cd76ae62',
   'v8/test/test262/harness':
     Var('chromium_url') + '/external/github.com/test262-utils/test262-harness-py.git' + '@' + '0f2acdd882c84cff43b9d60df7574a1901e2cdcd',
-  'v8/third_party/qemu': {
+  'v8/third_party/qemu-linux-x64': {
       'packages': [
           {
               'package': 'fuchsia/qemu/linux-amd64',
               'version': '9cc486c5b18a0be515c39a280ca9a309c54cf994'
           },
       ],
-      'condition': 'checkout_fuchsia',
+      'condition': 'host_os == "linux" and checkout_fuchsia',
       'dep_type': 'cipd',
   },
   'v8/tools/clang':