checker: apply stricter type checks to function args and return types

vlib/hash/crc32/crc32.v

@@ -58,6 +58,6 @@ pub fn new(poly int) &Crc32 {
 
 // calculate crc32 using ieee
 pub fn sum(b []byte) u32 {
-	c := new(ieee)
+	c := new(int(ieee))
 	return c.sum32(b)
 }

vlib/hash/crc32/crc32_test.v

@@ -7,7 +7,7 @@ fn test_hash_crc32() {
 	assert sum1.hex() == '483f8cf0'
 
 	
-	c := crc32.new(crc32.ieee)
+	c := crc32.new(int(crc32.ieee))
 	b2 := 'testing crc32 again'.bytes()
 	sum2 := c.checksum(b2)
 	assert sum2 == u32(1420327025)