go/ssa: rename some API features (incompatible change)

Rename the following exported names:
	(*Program).BuildAll → Build
	(*Program).Method   → MethodValue
	Package.Object      → Pkg
Also:
	(*Function).pkgobj  → pkg

Change-Id: Iff7e6c240ebe6786ba759278ac0daa3d66698013
Reviewed-on: https://go-review.googlesource.com/14134
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/go/pointer/gen.go b/go/pointer/gen.go
index 6c256ac..43849a2 100644
--- a/go/pointer/gen.go
+++ b/go/pointer/gen.go
@@ -1223,7 +1223,7 @@
 	// I think so, but the answer may depend on reflection.
 	mset := a.prog.MethodSets.MethodSet(T)
 	for i, n := 0, mset.Len(); i < n; i++ {
-		m := a.prog.Method(mset.At(i))
+		m := a.prog.MethodValue(mset.At(i))
 		a.valueNode(m)
 
 		if !itf {