Linter provides no warnings for invalid C code

See title, create a fresh test.c file with the contents:

#include <stdio.h>

int main()
{
    asdfd;
    return 0;
}

(If) Linting is working properly, asdfd will be underlined with squigglies as you would expect. What you would not expect is that turning it into a function call makes the squigglies go away:

#include <stdio.h>

int main()
{
    asdfd();
    return 0;
}

Furthermore, hovering over it produces the popup int asdfd(), as if it was defined to return int somewhere. This is just silly.

Related to #746

2つのスニペットを使って新しい test.c で動作を再現し、単独の無効な識別子と関数呼び出し形式を比較します。関連する issue #746 を読み、その再現をもとに C/C++ の lint と hover の動作を追跡します。両方の無効な形式が適切に診断され、呼び出しの hover に作られた int asdfd() が表示されなくなれば完了です。