checker: do not require fn main when building an object file

Author: medvednikov

vlib/v/checker/checker.v

@@ -368,7 +368,7 @@ pub fn (mut c Checker) check_files(ast_files []&ast.File) {
 	if !has_main_mod_file {
 		c.error('project must include a `main` module or be a shared library (compile with `v -shared`)',
 			token.Pos{})
-	} else if !has_main_fn {
+	} else if !has_main_fn && !c.pref.is_o {
 		c.error('function `main` must be declared in the main module', token.Pos{})
 	}
 }

vlib/v/gen/c/cgen.v

@@ -5486,8 +5486,9 @@ fn (mut g Gen) enum_val(node ast.EnumVal) {
 	// && g.inside_switch
 	if g.pref.translated && node.typ.is_number() {
 		// Mostly in translated code, when C enums are used as ints in switches
-		sym := g.table.sym(node.typ)
-		g.write('/* $node enum val is_number $node.mod styp=$styp sym=$sym*/_const_main__$node.val')
+		// sym := g.table.sym(node.typ)
+		// g.write('/* $node enum val is_number $node.mod styp=$styp sym=$sym*/_const_main__$node.val')
+		g.write('_const_main__$node.val')
 	} else {
 		g.write('${styp}__$node.val')
 	}