test: shared lib build doesn't handle SIGPIPE

For shared lib build, we leave the signal handling for embedding users.
In these two test cases:
- `parallel/test-process-external-stdio-close-spawn`
- `parallel/test-process-external-stdio-close`

The pipe is used for stdout and is destroied before child process uses
it for logging. So the node executble that uses shared lib build
receives SIGPIPE and the child process ends.

This change ignores the SIGPIPE in node_main.cc for shared lib case.

Refs: https://github.com/nodejs/node/issues/18535



Signed-off-by: Yihong Wang <yh.wang@ibm.com>

PR-URL: https://github.com/nodejs/node/pull/19211
Refs: https://github.com/nodejs/node/issues/18535


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Signed-off-by: Beth Griggs <Bethany.Griggs@uk.ibm.com>