Don't /LTCG CRT initializers

[CaseyCarter]

Fixes #2311

I verified the fix manually; open to suggestions for test coverage.

[AlexGuteniev]

After TryAcquireSRWLockExclusive is impoerted statically due to Vista drop, the only way to observe the difference would be __crtGetSystemTimePreciseAsFileTime, which affects system_clock::now() granularity. I don't think we need a test for it.

[StephanTLavavej]

I have manually verified the fix.

// cl /EHsc /nologo /W4 /MD /Zi /Fdmeow.pdb meow.cpp
#include <cstdio>
#include <mutex>
using namespace std;

int main() {
    mutex mut;
    puts("BEFORE");
    mut.lock();
    puts("DURING");
    mut.unlock();
    puts("AFTER");
}

Before this PR, stepping into mut.lock() eventually calls:

msvcp140_oss.dll!Concurrency::details::stl_critical_section_vista::lock()

After this PR, it calls:

msvcp140_oss.dll!Concurrency::details::stl_critical_section_win7::lock()

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[StephanTLavavej]

Thanks @AlexGuteniev for finding and @CaseyCarter for fixing this lurking bug! 🐞 🛠️ 😸