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

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=9c1d3869bab08d1a6e0255712b59dc0e59b44618

[jvoung (off chromium), 2015-03-31 16:40:41]

jvoung@chromium.org changed reviewers:
+ dschuff@chromium.org, kschimpf@google.com, mtrofin@chromium.org,
stichnot@chromium.org

[Jim Stichnoth, 2015-03-31 16:56:08]

lgtm

[Mircea Trofin, 2015-03-31 17:24:04]

lgtm

https://codereview.chromium.org/1041843003/diff/40001/src/IceBrowserCompileSe...
File src/IceBrowserCompileServer.cpp (right):

https://codereview.chromium.org/1041843003/diff/40001/src/IceBrowserCompileSe...
src/IceBrowserCompileServer.cpp:60: std::vector<char *> Argv;
you could just 
std::vector<char *> Argv(CLArgsLen + 1)

and then no need to reserve at line 62

[Jim Stichnoth, 2015-03-31 17:26:45]

https://codereview.chromium.org/1041843003/diff/40001/src/IceBrowserCompileSe...
File src/IceBrowserCompileServer.cpp (right):

https://codereview.chromium.org/1041843003/diff/40001/src/IceBrowserCompileSe...
src/IceBrowserCompileServer.cpp:60: std::vector<char *> Argv;
On 2015/03/31 17:24:04, Mircea Trofin wrote:
> you could just 
> std::vector<char *> Argv(CLArgsLen + 1)
> 
> and then no need to reserve at line 62

True, but then the push_back() calls have to be replaced with direct indexes and
you have to be more careful if you decide to push things in a different order,
so ...

[jvoung (off chromium), 2015-03-31 20:41:16]

https://codereview.chromium.org/1041843003/diff/40001/src/IceBrowserCompileSe...
File src/IceBrowserCompileServer.cpp (right):

https://codereview.chromium.org/1041843003/diff/40001/src/IceBrowserCompileSe...
src/IceBrowserCompileServer.cpp:60: std::vector<char *> Argv;
On 2015/03/31 17:26:44, stichnot wrote:
> On 2015/03/31 17:24:04, Mircea Trofin wrote:
> > you could just 
> > std::vector<char *> Argv(CLArgsLen + 1)
> > 
> > and then no need to reserve at line 62
> 
> True, but then the push_back() calls have to be replaced with direct indexes
and
> you have to be more careful if you decide to push things in a different order,
> so ...

Hmm, I'll stick with reserve() then. Another option could have been to use
SmallVector<char *, 16>, which should be good enough for most cases.

[jvoung (off chromium), 2015-03-31 21:14:27]

Committed patchset #3 (id:40001) manually as
9c1d3869bab08d1a6e0255712b59dc0e59b44618 (presubmit successful).