[lldb][Formatters] Simplify std::list libc++ formatter matching regex (#147709)
The history on this is a bit confusing. The libc++ regexes were adjusted
in https://reviews.llvm.org/D57466, and so did the order in which we
load the formatters. Then https://reviews.llvm.org/D66398 changed the
`std::list` regex, to make sure the libc++ formatters don't match the
`cxx11` libstdc++ [Dual ABI
namespace](https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html).
But we changed the order in which we load the formatters again in
https://github.com/llvm/llvm-project/pull/140727. The intention there
was to load libstdc++ first, because it may have inline namespaces that
would match relaxed the libc++ regexes. So that should technically make
this complicated regex workaround obsolete.
I didn't quite follow the entire thread in D66398 because some of the
links are dead. So it's possible something does rely on this. I'd like
to remove it and see. I *think* this should be resolved now by virtue of
how we load the formatters, but if it does break someone, there ought to
be a better solution (as Pavel hinted at in D66398).
llvm-project
98aa8407 - [lldb][Formatters] Simplify std::list libc++ formatter matching regex (#147709)
