runtime: fix nacl amd64p32 flakiness

newproc takes two extra pointers, not two extra registers.
On amd64p32 (nacl) they are different.

We diagnosed this before the 1.3 cut but the tree was frozen.
I believe this is causing the random problems on the builder.

Fixes #8199.

TBR=r
CC=golang-codereviews
https://golang.org/cl/102710043

diff --git a/src/pkg/runtime/traceback_x86.c b/src/pkg/runtime/traceback_x86.c
index f21469ba5977c99e8165e9b0b9db620e725be3c0..0ecaecf9cf28cce14aa79f9dbb3ec9c21ef277f9 100644 (file)
--- a/src/pkg/runtime/traceback_x86.c
+++ b/src/pkg/runtime/traceback_x86.c
@@ -214,7 +214,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
                // the SP is two words lower than normal.
                sparg = frame.sp;
                if(wasnewproc)
-                       sparg += 2*sizeof(uintreg);
+                       sparg += 2*sizeof(uintptr);
 
                // Determine frame's 'continuation PC', where it can continue.
                // Normally this is the return address on the stack, but if sigpanic