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

Reproduce the behavior in a fresh test.c using the two snippets, comparing the standalone invalid identifier with the function-call form. Read related issue #746 and trace the C/C++ linting and hover behavior from that reproduction. Done means both invalid forms are diagnosed appropriately and the call no longer gets a fabricated int asdfd() hover.