Make forkProcess work with +RTS -N

Consider this experimental for the time being.  There are a lot of
things that could go wrong, but I've verified that at least it works
on the test cases we have.

I also did some API cleanups while I was here.  Previously we had:

Capability * rts_eval (Capability *cap, HaskellObj p, /*out*/HaskellObj *ret);

but this API is particularly error-prone: if you forget to discard the
Capability * you passed in and use the return value instead, then
you're in for subtle bugs with +RTS -N later on.  So I changed all
these functions to this form:

void rts_eval (/* inout */ Capability **cap,
               /* in    */ HaskellObj p,
               /* out */   HaskellObj *ret)

It's much harder to use this version incorrectly, because you have to
pass the Capability in by reference.

1 files changed, 1 insertions, 1 deletions

diff --git a/rts/sm/GC.c b/rts/sm/GC.c
index 88d5a02f89..a4ac1fb01d 100644
--- a/rts/sm/GC.c
+++ b/rts/sm/GC.c
@@ -259,7 +259,7 @@ GarbageCollect (rtsBool force_major_gc,
    * We don't try to parallelise minor GCs (unless the user asks for
    * it with +RTS -gn0), or mark/compact/sweep GC.
    */
-  if (gc_type == PENDING_GC_PAR) {
+  if (gc_type == SYNC_GC_PAR) {
       n_gc_threads = RtsFlags.ParFlags.nNodes;
   } else {
       n_gc_threads = 1;