This patch has virtually no effect on anything (according to a
nofib run).  But it simplifies the definition of interesting_call
by being a bit less gung-ho about inlining nested function
bindings.  See Note [Nested functions]

-----------------------------------------------------------------------
        Program           Size    Allocs   Runtime   Elapsed  TotalMem
-----------------------------------------------------------------------
           anna          +0.2%     -0.0%     0.163     0.163      0.0%
   binary-trees          +0.1%     +0.0%     -4.5%     -4.5%      0.0%
      cacheprof          -0.1%     +0.1%     -4.7%     -4.8%     +2.7%
          fasta          +0.2%      0.0%     +2.6%     +3.0%      0.0%
          fluid          -0.0%     -0.6%     0.011     0.011      0.0%
         gamteb          -0.1%     -0.0%     0.069     0.070      0.0%
            hpg          +0.1%     +0.0%     +0.7%     +0.7%      0.0%
          infer          +0.3%     +0.2%     0.097     0.098      0.0%
         lambda          -0.1%     -0.0%     +2.0%     +2.0%      0.0%
         n-body          +0.1%     -0.1%     -0.1%     -0.1%      0.0%
         simple          -0.2%     -0.2%     +0.6%     +0.6%      0.0%
  spectral-norm          +0.1%     -0.0%     -0.1%     -0.1%      0.0%
            tak          -0.0%     -0.1%     0.024     0.024      0.0%
--------------------------------------------------------------------------------
            Min          -0.4%     -0.6%     -5.3%     -5.3%      0.0%
            Max          +0.3%     +0.2%     +3.3%     +3.3%    +15.0%
 Geometric Mean          -0.0%     -0.0%     -0.3%     -0.3%     +0.2%

(cherry picked from commit 33de71fa)

(This reverts the previous reversion in commit
9dbf66d7)