Add argv[0] before parsing commandline flags.
Add argv[0] before parsing commandline flags.

The \0 delimited string array that the browser sends doesn't have
the program name and the IRT only tokenizes that and forwards
it along. We need argv[0] to make the llvm CL parser happy
(used for -help message, etc).

Alternatively, we could have the IRT fill in a program name
so that the argv is a real argv. That will involve less copying since
the argv will be the right size to begin with, but prevents each app
from customizing its argv[0] =/

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4091
TEST= manual for now (construct the sel_universal script to only pass
the "--build-atts" flag and see it exits without being swallowed,
or pass "-Ofoo" and see an error + exit)

R=mtrofin@chromium.org, stichnot@chromium.org

Review URL: https://codereview.chromium.org/1041843003

bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader