doubled-up performIO

[Michael Hobbs]

When I nest a performIO inside another, I get a segmentation fault. What
I'm doing is invoking a C function which invokes a callback to Haskell
via performIO(). This callbacked function in Haskell then calls a C
function which invokes another performIO() function. At the point of the
second performIO() I get seg faults, bus errors, and/or core dumps (take
your pick). I'm using GHC 3.02 on Linux i386. (RedHat 5.1, to be exact)

- Michael Hobbs