go.tools/go/oracle: show import path (not just name) when describing an import.

+ test.

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/88190044

oracle/describe.go

@@ -498,7 +498,7 @@ func describePackage(o *Oracle, qpos *QueryPos, path []ast.Node) (*describePacka
 	switch n := path[0].(type) {
 	case *ast.ImportSpec:
 		pkgname := qpos.info.ImportSpecPkg(n)
-		description = fmt.Sprintf("import of package %q", pkgname.Name())
+		description = fmt.Sprintf("import of package %q", pkgname.Pkg().Path())
 		pkg = pkgname.Pkg()
 
 	case *ast.Ident:

oracle/testdata/src/main/imports.go

@@ -1,6 +1,7 @@
 package imports
 
 import (
+	"hash/fnv" // @describe ref-pkg-import2 "fnv"
 	"lib"      // @describe ref-pkg-import "lib"
 )
 
@@ -23,4 +24,6 @@ func main() {
 	print(*p + 1) // @pointsto p "p "
 
 	var _ lib.Type // @describe ref-pkg "lib"
+
+	fnv.New32()
 }

oracle/testdata/src/main/imports.golden

@@ -1,3 +1,10 @@
+-------- @describe ref-pkg-import2 --------
+import of package "hash/fnv"
+	func  New32  func() hash.Hash32
+	func  New32a func() hash.Hash32
+	func  New64  func() hash.Hash64
+	func  New64a func() hash.Hash64
+
 -------- @describe ref-pkg-import --------
 import of package "lib"
 	const Const untyped int = 3