Support target/host architecture with ninja iOS builds

When iOS builds support ninja and enable GYP_CROSSCOMPILE=1, ninja
will build breakpad, protoc and iossim using host arch instead
of the sub-out-ninja workaround.

TBR=mark@chromium.org
BUG=236517

Review URL: https://chromiumcodereview.appspot.com/14597007

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@199827 4ff67af0-8c30-449e-8e8b-ad334ec8d88c