IRT: Replace __attribute__((constructor)) with explicit call in _start()

IRT: Replace __attribute__((constructor)) with explicit call in _start()

The previous change to IrtInit() lets us remove the IrtInit()
definition from plugin_main_nacl.cc on the Chrome side.  This change
will let us remove the call to IrtInit() from plugin_main_nacl.cc as
well.

The __attribute__((constructor)) function reportedly wasn't getting
run in the ARM build.  Doing an explicit call to IrtInit() is cleaner
and doesn't rely on linker tricks.

This requires declaring irt_support_private's dependency on libsrpc
etc. in library_deps.py so that tests/irt_compatibility continues to
link.  (Previously, its custom IRT wasn't including the IrtInit()
call.)

Also clean up the build so that irt_entry.o isn't treated specially.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3186
TEST=run_irt_compatibility_test_irt run_random_test_irt + Chrome trybots

Committed: https://src.chromium.org/viewvc/native_client?view=rev&revision=11819

[Roland McGrath, 2013-07-19 21:28:16]

LGTM with the caveat that I'm already nauseated by the inclusion of srpc,
nacllog, etc. in irt_core.nexe.

[Mark Seaborn, 2013-07-20 00:41:01]

Committed patchset #2 manually as r11819 (presubmit successful).

[Mark Seaborn, 2013-07-20 00:41:47]

On 2013/07/19 21:28:16, Roland McGrath wrote:
> LGTM with the caveat that I'm already nauseated by the inclusion
> of srpc, nacllog, etc. in irt_core.nexe.

Yes, so am I. :-(