NaCl: Fix socket FD leak in NaCl process startup on Unix
NaCl: Fix socket FD leak in NaCl process startup on Unix

The dup() call was unnecessary.  The subsequent call,
  internal_->sockets_for_sel_ldr.clear()
frees the array contents and prevents ~NaClProcessHost() from closing
the FDs.

The leak is bad because it will cause a renderer process to hang if
the NaCl process crashes during startup.  Worse, the file descriptor
table of the browser process will eventually become full.

The Mac-specific dup() call should be correct, however, because the
destructor for base::SharedMemory closes its FD.

BUG=90611
TEST=manual: on Linux, added printf() to log the file descriptor number
 * before: the FD numbers increase
 * after: the FD numbers hover around 83-87

Review URL: http://codereview.chromium.org/7477023

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@94240 0039d316-1c4b-4281-b951-d872f2087c98

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