Fix static analysis warnings

[StephanTLavavej]

The MSVC-internal repo is making another push to enable and clean up static analysis warnings in the build. The STL was previously unaffected as we've built our tests with plain /analyze for 3000 years, but now additional rulesets are being enabled and the STL is emitting warnings.

• Add empty braces to fix warning C26495 "Variable 'MEOW' is uninitialized. Always initialize a member variable (type.6)."
  • This is safe because Zero Is A Strict Subset Of Garbage.
• Permanently silence warning C26495 (uninitialized member variable) for _Big_integer_flt::_Mydata.
  • As the big comment explains, leaving this uninitialized is important for performance.
• Fix warning C28252 "Inconsistent annotation for 'RtlCaptureStackBackTrace': return/function has 'SAL_success(return!=0)' on the prior instance. See [...]\winnt.h(20721)."
  • The return annotation was indeed missing.
• Fix warning C26439 "This kind of function should not throw. Declare it 'noexcept' (f.6)."
  • Add noexcept(false) because these move ctors call basic_ios::init() => ios_base::_Init() => new locale.
  • list dynamically allocates a sentinel node.
• Fix warning C26450 "Arithmetic overflow: '-' operation causes overflow at compile time. Use a wider type to store the operands (io.1)." and warning C26454 "Arithmetic overflow: '-' operation produces a negative unsigned result at compile time (io.5)."
  • We can avoid these warnings by directly forming the values, which is also easier to read.

    C:\Temp>type meow.cpp
    

    #include <climits>
    #include <iostream>
    using namespace std;
    
    static_assert((1ul << 31) == 0 - static_cast<unsigned long>(LONG_MIN));
    static_assert((1ull << 63) == 0 - static_cast<unsigned long long>(LLONG_MIN));
    
    int main() {
        cout << 0 - static_cast<unsigned long>(LONG_MIN) << endl;
        cout << (1ul << 31) << endl;
    
        cout << 0 - static_cast<unsigned long long>(LLONG_MIN) << endl;
        cout << (1ull << 63) << endl;
    }

    C:\Temp>cl /EHsc /nologo /W4 meow.cpp && meow
    meow.cpp
    2147483648
    2147483648
    9223372036854775808
    9223372036854775808
    

• Silence warning C26110 "Caller failing to hold lock 'MEOW' before calling function 'ReleaseSRWLockExclusive'."
  • We're implementing lock machinery, so we have to assume that the lock is held here.
• In <charconv>, work around VSO-1826196 "False positive C26454 in charconv". This has already been fixed in the latest compiler sources, we just need to wait for the MSVC-internal toolset to be updated. Thanks to @dmitrykobets-msft for investigating this.

[StephanTLavavej]

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

[StephanTLavavej]

Added one more change before mirroring.