Most of the cases were where a C++ file was being compiled with the C substitution.
There were a few cases of the opposite though.
LLDB seems to be the only real culprit in the LLVM codebase for these mismatches.
Rest of the LLVM presumably sticks at least language-specific options in the common substitutions
making the mistakes immediately apparent.
I found these by using Clang frontend configuration files containing language-specific options for
both C and C++ (e.g. `-std=c2y` and `-std=c++26`).
We skip/xfail the other FrameFormat tests on Windows already. The number
of different buildbot configurations out there targetting Windows makes
it hard to make this test portable. If we want to test this on Windows
we should probably just make a dedicated test for it.
This patch adds another frame-format variable (currently only
implemented in the CPlusPlus language plugin) that represents the
"suffix" of a function. The name is derived from the `DotSuffix` node of
LLVM's Itanium demangler.
For a function name such as `int foo() (.cold)`, the suffix would be
`(.cold)`.
