This PR adds type summaries for
`std::{string,wstring,u8string,u16string,u32string}` from the MSVC STL.
See https://github.com/llvm/llvm-project/issues/24834 for the MSVC STL
issue.
The following changes were made:
- `dotest.py` now detects if the MSVC STL is available. It does so by
looking at the target triple, which is an additional argument passed
from Lit. It specifically checks for `windows-msvc` to not match on
`windows-gnu` (i.e. MinGW/Cygwin).
- (The main part): Added support for summarizing `std::(w)string` from
MSVC's STL. Because the type names from the libstdc++ (pre C++ 11)
string types are the same as on MSVC's STL, `CXXCompositeSummaryFormat`
is used with two entries, one for MSVC's STL and one for libstdc++.
With MSVC's STL, `std::u{8,16,32}string` is also handled. These aren't
handled for libstdc++, so I put them in `LoadMsvcStlFormatters`.
45689b26eb