go/ssa: change import path of synthetic test package to "test$main"

...to avoid namespace conflicts.
Also make its name "main", since it defines func main().

And fix 2 typos.

Change-Id: I7cf7894d6bed134907b3d2742255e5a82426071b
Reviewed-on: https://go-review.googlesource.com/3150
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/refactor/importgraph/graph.go b/refactor/importgraph/graph.go
index 6f49fab..df73e23 100644
--- a/refactor/importgraph/graph.go
+++ b/refactor/importgraph/graph.go
@@ -51,7 +51,7 @@
 	return seen
 }
 
-// Builds scans the specified Go workspace and builds the forward and
+// Build scans the specified Go workspace and builds the forward and
 // reverse import dependency graphs for all its packages.
 // It also returns a mapping from import paths to errors for packages
 // that could not be loaded.