check unused and unmodified vars in all modules, not just main

vlib/hash/crc32/crc32.v

@@ -36,7 +36,7 @@ fn(c mut Crc32) generate_table(poly int) {
 		c.table << crc
 	}
 }
- 
+
 fn(c &Crc32) sum32(b []byte) u32 {
 	mut crc := ~u32(0)
 	for i := 0; i < b.len; i++ {
@@ -58,6 +58,6 @@ pub fn new(poly int) &Crc32 {
 
 // calculate crc32 using ieee
 pub fn sum(b []byte) u32 {
-	mut c := new(ieee)
+	c := new(ieee)
 	return c.sum32(b)
 }