[PATCH 0/4] xfsdump: convert to using the POSIX signal API

[Bill Kendall]

This patch series converts xfsdump from using the System V signal
API to using the POSIX API. The first 3 patches remove/rework some
of the existing signal code, and the final patch does the actual
conversion.

The primary motivatation for this change is a currently unused
section of code in xfsdump's main():

    /* sleep until next signal
     */
    sigrelse(SIGINT);
    sigrelse(SIGHUP);
    ...
    sigpause(SIGARLM);

The intention is to wake up if any of the signals is received, but
this will only wake up if SIGALRM is received. Using sigsuspend()
with the appropriate mask fixes the issue.