parser: make spawn behave like go

vlib/v/parser/expr.v

@@ -114,7 +114,7 @@ pub fn (mut p Parser) check_expr(precedence int) !ast.Expr {
 				node = p.prefix_expr()
 			}
 		}
-		.key_go {
+		.key_go, .key_spawn {
 			mut go_expr := p.go_expr()
 			go_expr.is_expr = true
 			node = go_expr

vlib/v/parser/parser.v

@@ -1051,7 +1051,7 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 				}
 			}
 		}
-		.key_go {
+		.key_go, .key_spawn {
 			go_expr := p.go_expr()
 			return ast.ExprStmt{
 				expr: go_expr

vlib/v/tests/inout/go_print.out

@@ -1 +1,2 @@
 [1, 2, 3]
+[4,5, 6]

vlib/v/tests/inout/go_print.vv

@@ -1,4 +1,7 @@
 fn main(){
 	g := go print([1, 2, 3])
 	g.wait()
+	println('')
+	g2 := spawn print([4, 5, 6])
+	g2.wait()
 }