Execute the per-platform initialization logic as early as possible,
for two reasons:

1. It opens the way for an upcoming commit to simplify early SIGUSR1
   handling.

2. It should make life easier for embedders because io.js no longer
   mucks around with the file descriptor limit or signal disposition
   of the process.

PR-URL: nodejs#615
Reviewed-By: Sam Roberts <sam@strongloop.com>

Instead of installing an early debug signal handler, simply block the
SIGUSR1 signal at start-up and unblock it when the debugger is ready.

Both approaches are functionally equivalent but blocking the signal
accomplishes it in fewer lines of code.

PR-URL: nodejs#615
Reviewed-By: Sam Roberts <sam@strongloop.com>

Signal dispositions are inherited by child processes.  Restore ours to
sane defaults in case our parent process changed it, to prevent quirky
behavior when the parent does something silly like ignoring SIGSEGV.

PR-URL: nodejs#615
Reviewed-By: Sam Roberts <sam@strongloop.com>

An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

An application using node built as a shared library may legitimately
implement its own signal handling routines. Current behaviour is
to squash all signal handlers on node startup. This change will
stop that behaviour when node is built as a shared library.

PR-URL: #10539
Fixes: #10520
Refs: #615
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>