Add a bitcode parser constructor for parallel parsing.

Allows the caller of the constructor to provide the bitstream cursor to
use, rather than inheriting from the enclosing parser. This allows each
parallel parse (of subblocks) to create thier own bitcode cursor.

BUG= https://bugs.chromium.org/p/nativeclient/issues/detail?id=4363
R=jpp@chromium.org, stichnot@chromium.org

Review URL: https://codereview.chromium.org/1831493003 .
1 file changed