pmmgr scaling: don't cry on a SIGPIPE
pmmgr scaling: don't cry on a SIGPIPE

It has been reported that on some heavily loaded systems, pmmgr
can intermittently die with a "too many interrupts" message.  Analysis
with systemtap indicates that these events come from SIGPIPE's being
sent by the kernel from within a
 __pmSend
 __pmXmitPDU
 __pmSendNameList
 pmLookupName
 ....
 __dmopencontext
 pmNewContext
call chain.  Presumably, a remote pmcd died mid-conversation, and
pdu.c's SIGPIPE ignoring logic didn't help enough.

pmmgr should not look for SIGPIPE anyway as a termination signal - we
don't produce output on stdout like a pipeable UNIX tool.  We now
SIG_IGN it.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp