[GHC] #15741: Accept GHCRTS=-N1 when not compiled with -threaded

[GHC]

#15741: Accept GHCRTS=-N1 when not compiled with -threaded
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        Reporter:  lspitzner         |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Runtime System    |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by lspitzner):

 There also is the more general feature request "support passing rts opts
 in a ignore-if-unsupported" mode. E.g. with a system-wide "GHCRTS=-M1G"
 even running cabal install flat-out fails because cabal does not compile
 `Setup.hs`s with -rtsopts. Might be considered a bug in cabal in that
 case, but some escape hatch might make sense regardless. Maybe a second
 env var, like "GHCRTSSOFT" or something? Thoughts?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15741#comment:1>
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