re PR go/77642 (GO Bootstrap fail starting with r239872 splitstack signature does not match)

	PR go/77642

    runtime: pass correct type to __splitstack_find
    
    The code was passing uintptr* to a function that expected size_t*.
    
    Based on patch by Andreas Krebbel.
    
    Fixes GCC PR 77642.
    
    Reviewed-on: https://go-review.googlesource.com/29433

From-SVN: r240275

gcc/go/gofrontend/MERGE

-b34c93bf00ec4f2ad043ec89ff96989e0d1b26aa
+80720773ac1a3433b7de59ffa5c04744123247c3
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/runtime/proc.c

@@ -2052,9 +2052,13 @@ doentersyscall()
 
 	// Leave SP around for GC and traceback.
 #ifdef USING_SPLIT_STACK
-	g->gcstack = __splitstack_find(nil, nil, &g->gcstacksize,
+	{
+	  size_t gcstacksize;
+	  g->gcstack = __splitstack_find(nil, nil, &gcstacksize,
 					 &g->gcnextsegment, &g->gcnextsp,
 					 &g->gcinitialsp);
+	  g->gcstacksize = (uintptr)gcstacksize;
+	}
 #else
 	{
 		void *v;
@@ -2099,9 +2103,13 @@ runtime_entersyscallblock(void)
 
 	// Leave SP around for GC and traceback.
 #ifdef USING_SPLIT_STACK
-	g->gcstack = __splitstack_find(nil, nil, &g->gcstacksize,
+	{
+	  size_t gcstacksize;
+	  g->gcstack = __splitstack_find(nil, nil, &gcstacksize,
 					 &g->gcnextsegment, &g->gcnextsp,
 					 &g->gcinitialsp);
+	  g->gcstacksize = (uintptr)gcstacksize;
+	}
 #else
 	g->gcnextsp = (byte *) &p;
 #endif