Ignore iovec::iov_base that requires .get() in a different repository

The pointer is used for reinterpret_cast in:
net/third_party/quiche/src/quic/core/qpack/qpack_receive_stream.cc:29
net/third_party/quiche/src/quic/core/http/quic_spdy_stream.cc:773
net/third_party/quiche/src/quic/core/http/quic_spdy_stream_body_manager.cc:99

Bug: 1069567
Change-Id: If0c54da8255f312f047bc3da6c35c601e8d868d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2509891Reviewed-by: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Bartek Nowierski <bartekn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822898}

tools/clang/rewrite_raw_ptr_fields/manual-fields-to-ignore.txt

@@ -114,6 +114,8 @@ performance_manager::v8_memory::(anonymous namespace)::V8ContextTrackerTest::tra
 content::(anonymous namespace)::BackForwardCacheMessageFilter::interface_name_
 
 # Populated manually - other compile-time reasons
+iovec::iov_base  # requires adding .get() in another repository, used e.g. in
+                 # reinterpret_cast in quic_stream_sequencer_buffer.cc
 views::internal::ClassPropertySetter::property_  # passed to templated param T*
 (anonymous namespace)::ScopedFunctionHelper::function_ # function pointer template