There's no reason to support any other encoding in these files.
This only affects the files themselves and not streams they open.
Bug: https://crbug.com/gerrit/10418
Change-Id: I053cb40cd3666ce5c8a0689b9dd938f24ca765bf
The value of the varible TRACE was copied during the import, which
happens before the --trace option can be processed. So instead we
now use a function to determine if the value is set, as the function
can be safely copied early during import.
Signed-off-by: Shawn O. Pearce <sop@google.com>