runtime: enable StackCopyAlways

Let's see how close we are to this being ready.
Will roll back if it breaks any builds in non-trivial ways.

LGTM=r, khr
R=iant, khr, r
CC=golang-codereviews
https://golang.org/cl/138200043

diff --git a/src/runtime/stack.c b/src/runtime/stack.c
index bb8c7ac11b8a9b0bc4b90770f0a24f89d6b72568..ca0eed06f983b773942613579b30b2136230369c 100644 (file)
--- a/src/runtime/stack.c
+++ b/src/runtime/stack.c
@@ -26,7 +26,7 @@ enum
 
        StackCache = 1,
        
-       StackCopyAlways = 0,    // expect to be able to copy stacks 100% of the time
+       StackCopyAlways = 1,    // expect to be able to copy stacks 100% of the time
 };
 
 // Global pool of spans that have free stacks.