V.js: remove u8

vlib/builtin/js/int.v

@@ -37,10 +37,6 @@ pub fn (nn u32) str() string {
 	return '0'
 }
 
-pub fn (nn u8) str() string {
-	return '0'
-}
-
 pub fn (nn i64) str() string {
 	return '0'
 }

vlib/compiler/cheaders.v

@@ -168,7 +168,6 @@ var u64 = function() {}
 var u32 = function() {}
 var u16 = function() {}
 var i8 = function() {}
-var u8 = function() {}
 var bool = function() {}
 var rune = function() {}
 var map_string = function() {}