runtime: move schedt type and sched var from C to Go

This doesn't change any actual code, it just starts using the Go
    definition of the schedt type and the sched variable rather than the C
    definitions.
    
    The schedt type is tweaked slightly for gccgo.  We aren't going to
    release goroutine stacks, so we don't need separate gfreeStack and
    gfreeNostack lists.  We only have one size of defer function, so we
    don't need a list of 5 different pools.
    
    Reviewed-on: https://go-review.googlesource.com/33364

From-SVN: r242600

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-fc4ca600b2fc6de81fd3c4014542d6a50593db1a
+bf4762823c4543229867436399be3ae30b4d13bb
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/runtime/runtime2.go

@@ -550,9 +550,6 @@ const (
 	_MaxGomaxprocs = 1 << 8
 )
 
-/*
-Commented out for gccgo for now.
-
 type schedt struct {
 	// accessed atomically. keep at top to ensure alignment on 32-bit systems.
 	goidgen  uint64
@@ -578,18 +575,17 @@ type schedt struct {
 	runqsize int32
 
 	// Global cache of dead G's.
-	gflock       mutex
-	gfreeStack   *g
-	gfreeNoStack *g
-	ngfree       int32
+	gflock mutex
+	gfree  *g
+	ngfree int32
 
 	// Central cache of sudog structs.
 	sudoglock  mutex
 	sudogcache *sudog
 
-	// Central pool of available defer structs of different sizes.
+	// Central pool of available defer structs.
 	deferlock mutex
-	deferpool [5]*_defer
+	deferpool *_defer
 
 	gcwaiting  uint32 // gc is waiting to run
 	stopwait   int32
@@ -608,7 +604,6 @@ type schedt struct {
 	procresizetime int64 // nanotime() of last change to gomaxprocs
 	totaltime      int64 // ∫gomaxprocs dt up to procresizetime
 }
-*/
 
 // The m.locked word holds two pieces of state counting active calls to LockOSThread/lockOSThread.
 // The low bit (LockExternal) is a boolean reporting whether any LockOSThread call is active.
@@ -772,8 +767,10 @@ var (
 
 	ncpu int32
 
-//	forcegc     forcegcstate
-//	sched       schedt
+	//	forcegc     forcegcstate
+
+	sched schedt
+
 //	newprocs    int32
 
 // Information about what cpu features are available.

libgo/go/runtime/stubs.go

@@ -520,3 +520,9 @@ func dumpregs(*_siginfo_t, unsafe.Pointer)
 
 // Temporary for gccgo until we port panic.go.
 func startpanic()
+
+// Temporary for gccgo until we port proc.go.
+//go:linkname getsched runtime.getsched
+func getsched() *schedt {
+	return &sched
+}