Remove set-but-unused variable to appease newly rolled Clang

Unblocks the clang rollers.

Trivial and safe alternative to adding:
      -Wno-unused-but-set-parameter
      -Wno-unused-but-set-variable
to cflags, which doesn't seem to impact this file.

Change-Id: Id4c84604852d29920867f75ff8d953eef26337c8
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/harfbuzz/+/549976
Reviewed-by: Jason Simmons <jsimmons@google.com>
1 file changed