parser: parse non-identifier expressions for sizeof too (#7781)

vlib/v/tests/sizeof_test.v

@@ -1,6 +1,17 @@
 import math
 
-fn test_sizeof() {
+struct S1 {
+	i voidptr
+}
+
+fn test_math_sizeof() {
 	r := math.f32_from_bits(sizeof(int))
 	assert r > 5.6e-45 && r < 5.7e-45
 }
+
+fn test_sizeof() {
+	// depends on compiler
+	assert sizeof(`€`) in [u32(2), 4]
+	// depends on -m32/64
+	assert sizeof(S1) in [u32(4), 8]
+}