checker: remove unnecessary "no methods" error; builder: skip float.c.v with -nofloat

vlib/builtin/float.c.v

@@ -2,6 +2,8 @@
 // Use of this source code is governed by an MIT license that can be found in the LICENSE file.
 module builtin
 
+// TODO implement compile time conditional include
+// [if !nofloat]
 import strconv
 
 #include <float.h>