Fix GDA not visiting global operator delete

[DutChen18]

When GlobalDepsAnalyzer encounters a function where isFreeFunctionName returns true, that function is not visited immediately. Instead, a flag is set indicating that a function named "free" should be visited later, if needed.

When isFreeFunctionName returns true for a function whose name is not "free" (so "_ZdlPv" or "_ZdaPv"), that function will never be visited by GDA. This results in a crash when the function references any other global that is deleted as a result of the function, and its children, not being visited.

Example of a program that would crash:

#include <cstdio>

void operator delete(void* ptr) noexcept {
        std::puts("test");
}

int main() {
        delete new int;
}

I don't see any point in defering visiting the global delete operators, so the solution is to simply replace the call to isFreeFunctionName so we only defer visiting the function named "free". Note that isFreeFunctionName is still used in other places where it should probably return true for the global delete operators as well.