[lldb] Fix build break on windows (#84863)

This is a one line fix for a Windows specific (I believe) build break.

The build failure looks like this:
`D:\a\_work\1\s\lldb\source\Symbol\Symtab.cpp(128): error C2440:
'<function-style-cast>': cannot convert from 'lldb_private::ConstString'
to 'llvm::StringRef'
D:\a\_work\1\s\lldb\source\Symbol\Symtab.cpp(128): note:
'llvm::StringRef::StringRef': ambiguous call to overloaded function
D:\a\_work\1\s\llvm\include\llvm/ADT/StringRef.h(840): note: could be
'llvm::StringRef::StringRef(llvm::StringRef &&)'
D:\a\_work\1\s\llvm\include\llvm/ADT/StringRef.h(104): note: or
'llvm::StringRef::StringRef(std::string_view)'
D:\a\_work\1\s\lldb\source\Symbol\Symtab.cpp(128): note: while trying to
match the argument list '(lldb_private::ConstString)'
D:\a\_work\1\s\lldb\source\Symbol\Symtab.cpp(128): error C2672:
'std::multimap<llvm::StringRef,const lldb_private::Symbol
*,std::less<llvm::StringRef>,std::allocator<std::pair<const
llvm::StringRef,const lldb_private::Symbol *>>>::emplace': no matching
overloaded function found
C:\Program Files\Microsoft Visual
Studio\2022\Enterprise\VC\Tools\MSVC\14.37.32822\include\map(557): note:
could be
'std::_Tree_iterator<std::_Tree_val<std::_Tree_simple_types<std::pair<const
llvm::StringRef,const lldb_private::Symbol *>>>>
std::multimap<llvm::StringRef,const lldb_private::Symbol
*,std::less<llvm::StringRef>,std::allocator<std::pair<const
llvm::StringRef,const lldb_private::Symbol *>>>::emplace(_Valty &&...)'
`

The StringRef constructor here is intended to take a ConstString object,
which I assume is implicitly converted to a std::string_view by
compilers other than Visual Studio's. To fix the VS build I made the
StringRef initialization more explicit, as you can see in the diff.

0 files changed, 0 insertions, 0 deletions