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>

vlib/v/checker/checker.v

@@ -2144,7 +2144,9 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 		}
 	}
 	if left_type == ast.void_type {
-		c.error('`void` type has no methods', node.left.position())
+		// No need to print this error, since this means that the variable is unknown,
+		// and there already was an error before.
+		// c.error('`void` type has no methods', node.left.position())
 		return ast.void_type
 	}
 	mut has_generic := false // x.foo<T>() instead of x.foo<int>()

vlib/v/pref/should_compile.v

@@ -30,6 +30,9 @@ pub fn (prefs &Preferences) should_compile_filtered_files(dir string, files_ []s
 		if file.starts_with('.#') {
 			continue
 		}
+		if prefs.nofloat && file.ends_with('float.c.v') {
+			continue
+		}
 		if file.contains('_d_') {
 			if prefs.compile_defines_all.len == 0 {
 				continue