[libgo] Fix alignment issue in persistent allocator

[Eric Botcazou]

This gets rid of a bunch of Go failures on SPARC.

Tested on x86-64/Linux, SPARC/Solaris and SPARC64/Linux.


2019-02-16  Eric Botcazou  <ebotca...@adacore.com>

        * go/runtime/malloc.go (persistentalloc1): Always align the offset.

-- 
Eric Botcazou
Index: go/runtime/malloc.go
===================================================================
--- go/runtime/malloc.go	(revision 268849)
+++ go/runtime/malloc.go	(working copy)
@@ -1269,7 +1269,7 @@ func persistentalloc1(size, align uintpt
 				break
 			}
 		}
-		persistent.off = sys.PtrSize
+		persistent.off = round(sys.PtrSize, align)
 	}
 	p := persistent.base.add(persistent.off)
 	persistent.off += size