Fix encoding when communicating with ninja

Ninja escapes UTF-8 symbols in some cases, and it causes errors when
parsing ninja commands, for example:
https://source.chromium.org/chromium/chromium/src/+/main:third_party/rust/strsim/v0_10/BUILD.gn;l=24;drc=42a40ac8eb5420b0b7ff7142102ed4bed479e6c4

Tested locally.

Bug: None
Change-Id: If2dae9b15b5ee664d90f92e3669598f7ba229a56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4623929
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Rushan Suleymanov <rushans@google.com>
Cr-Commit-Position: refs/heads/main@{#1159478}
NOKEYCHECK=True
GitOrigin-RevId: f2b12faba4d1bcc0554e69bfe7718435d43998ac