database/sql: add NullInt64, NullFloat64, NullBool

Fixes #2699

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5557063
diff --git a/src/pkg/database/sql/fakedb_test.go b/src/pkg/database/sql/fakedb_test.go
index b0d137c..df25023 100644
--- a/src/pkg/database/sql/fakedb_test.go
+++ b/src/pkg/database/sql/fakedb_test.go
@@ -585,12 +585,26 @@
 	switch typ {
 	case "bool":
 		return driver.Bool
+	case "nullbool":
+		return driver.Null{driver.Bool}
 	case "int32":
 		return driver.Int32
 	case "string":
 		return driver.NotNull{driver.String}
 	case "nullstring":
 		return driver.Null{driver.String}
+	case "int64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.NotNull{driver.DefaultParameterConverter}
+	case "nullint64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.Null{driver.DefaultParameterConverter}
+	case "float64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.NotNull{driver.DefaultParameterConverter}
+	case "nullfloat64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.Null{driver.DefaultParameterConverter}
 	case "datetime":
 		return driver.DefaultParameterConverter
 	}