Wrong stack space size when using -Ksize
After compiling the first example in https://wiki.haskell.org/Performance/Accumulating_parameter:
```
$ cat Test.hs
len :: [a] -> Int
len [] = 0
len (x:xs) = len xs + 1
main :: IO ()
main = print $ len [1..1000000]
```
```
$ ghc Test.hs -rtsopts
```
and running
```
./Test +RTS -K10K
```
GHC 7.6.3 reports
```
Stack space overflow: current size 10240 bytes.
```
GHC 7.8.4 reports
```
Stack space overflow: current size 33632 bytes.
```
GHC 7.10.1 reports
```
Stack space overflow: current size 99136 bytes.
```
and GHC 7.10.2, 7.10.3. 8.0.1 and 8.0.2-rc1 report
```
Stack space overflow: current size 33624 bytes.
```
GHC \>= 7.8.4 report an incorrect stack space size.
issue