WIP: compiler: Don't inline panic functions

While working on making runRW# simplify (#15127 (closed)) I noticed that we tend to inline these panic functions pretty ubiquitously. For instance, in GHC.CmmToAsm.PPC.Regs we alone inlined PlainPanic.panic six times, each of which generating a 20-something term binding, each differing only in the error message string. For instance,

-- RHS size: {terms: 17, types: 41, coercions: 0, joins: 0/0}
GHC.CmmToAsm.PPC.Regs.regDotColor2
  :: GHC.Prim.State# GHC.Prim.RealWorld -> Outputable.SDoc
[GblId, Arity=1, Str=<L,U>, Cpr=b, Unf=OtherCon []]
GHC.CmmToAsm.PPC.Regs.regDotColor2
  = \ (eta_s8Vu [Occ=Once] :: GHC.Prim.State# GHC.Prim.RealWorld) ->
      case GHC.Prim.getCurrentCCS#
             @GHC.Base.String @GHC.Prim.RealWorld x1_r7VT eta_s8Vu
      of
      { (# s'_s8Vw [Occ=Once], addr_s8Vx [Occ=Once] #) ->
      case GHC.Stack.CCS.$wgo
             addr_s8Vx (GHC.Types.[] @[GHC.Types.Char]) s'_s8Vw
      of
      { (# ipv_s8Vz [Occ=Once], ipv1_s8VA [Occ=Once] #) ->
      case PlainPanic.panic1
             @GHC.Platform.Reg.Class.RegClass ipv_s8Vz ipv1_s8VA x1_r7VT
      of {
      }
      }
      }

Given how this is a failure path, this seems silly. Frankly, it's surprising that we choose to inline at all. Part of me things that we should apply some sort of penalty for inlining a bottoming function.

This is tracked as #18086 (closed).