Fix some missed opportunities for preInlineUnconditionally

There are two signficant changes here:

* Ticket #18815 showed that we were missing some opportunities for
  preInlineUnconditionally.  The one-line fix is in the code for
  GHC.Core.Opt.Simplify.Utils.preInlineUnconditionally, which now
  switches off only for INLINE pragmas.  I expanded
  Note [Stable unfoldings and preInlineUnconditionally] to explain.

* When doing this I discovered a way in which preInlineUnconditionally
  was occasionally /too/ eager.  It's all explained in
  Note [Occurrences in stable unfoldings] in GHC.Core.Opt.OccurAnal,
  and the one-line change adding markAllMany to occAnalUnfolding.

I also got confused about what NoUserInline meant, so I've renamed
it to NoUserInlinePrag, and changed its pretty-printing slightly.
That led to soem error messate wibbling, and touches quite a few
files, but there is no change in functionality.

I did a nofib run.  As expected, no significant changes.

        Program           Size    Allocs
----------------------------------------
         sphere          -0.0%     -0.4%
----------------------------------------
            Min          -0.0%     -0.4%
            Max          -0.0%     +0.0%
 Geometric Mean          -0.0%     -0.0%

I'm allowing a max-residency increase for T10370, which seems
very irreproducible. (See comments on !4241.)  There is always
sampling error for max-residency measurements; and in any case
the change shows up on some platforms but not others.

Metric Increase:
    T10370

1 files changed, 5 insertions, 5 deletions

diff --git a/compiler/GHC/Utils/Binary.hs b/compiler/GHC/Utils/Binary.hs
index d4afa624cf..2975ab2d0d 100644
--- a/compiler/GHC/Utils/Binary.hs
+++ b/compiler/GHC/Utils/Binary.hs
@@ -1311,14 +1311,14 @@ instance Binary RuleMatchInfo where
                       else return FunLike
 
 instance Binary InlineSpec where
-    put_ bh NoUserInline    = putByte bh 0
-    put_ bh Inline          = putByte bh 1
-    put_ bh Inlinable       = putByte bh 2
-    put_ bh NoInline        = putByte bh 3
+    put_ bh NoUserInlinePrag = putByte bh 0
+    put_ bh Inline           = putByte bh 1
+    put_ bh Inlinable        = putByte bh 2
+    put_ bh NoInline         = putByte bh 3
 
     get bh = do h <- getByte bh
                 case h of
-                  0 -> return NoUserInline
+                  0 -> return NoUserInlinePrag
                   1 -> return Inline
                   2 -> return Inlinable
                   _ -> return NoInline