cgen: fix generic options with reserved ident (fix #22163)

[yuyi98]

This PR fix generic options with reserved ident (fix #22163).

• Fix generic options with reserved ident.
• Add test.

pub fn f[T](defaults ?T) T {
	default := defaults or { T{} }
	dump(default)
	return default
}

fn main() {
	ret1 := f(123)
	println(ret1)
	assert ret1 == 123

	ret2 := f('hello')
	println(ret2)
	assert ret2 == 'hello'
}

PS D:\Test\v\tt1> v run .       
[.\\tt1.v:3] default: 123
123
[.\\tt1.v:3] default: hello
hello

[spytheman]

Excellent work.
Thank you.