[GHC] #9029: [CID43142] Check return value of sigaction

[GHC]

#9029: [CID43142] Check return value of sigaction
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       Reporter:  nicolast          |             Owner:  simonmar
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Runtime System    |           Version:  7.8.2
       Keywords:  coverity          |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 Coverity pointed at a location where the return value of sigaction isn't
 checked, unlike other occurrences of the function call.

 This patch adds the call, in line with other code.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9029>
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