cgen: support inc cond for c style for loop with alias types (#21708)

vlib/v/gen/c/assign.v

@@ -520,7 +520,9 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 					g.expr(left)
 					g.write(' ${extracted_op} ')
 					g.expr(val)
-					g.write(';')
+					if !g.inside_for_c_stmt {
+						g.write(';')
+					}
 					return
 				} else {
 					g.write(' = ${styp}_${util.replace_op(extracted_op)}(')

vlib/v/tests/alias_assigned_in_increment_part_of_for_c_loop_test.v

@@ -0,0 +1,11 @@
+type Float = f32
+
+fn test_increment_of_alias_in_for_c_loop() {
+	min_value := Float(1)
+	max_value := Float(10)
+	step := Float(1)
+	for n := min_value; n <= max_value; n += step {
+		println('${n}')
+		assert n > 0.0 && n < 11.0
+	}
+}