Allow disabling LTO on eng

Test: Verified setting never to true in hwui resulted
in a fast incremental build
Bug: 111277863

Change-Id: Ic3da6f3adc2c97f0d5f287402c460907533a5f71

android/variable.go

@@ -92,6 +92,9 @@ type variableProperties struct {
 		Eng struct {
 			Cflags   []string
 			Cppflags []string
+			Lto      struct {
+				Never *bool
+			}
 		}
 
 		Pdk struct {