[lldb] Fix editline unicode on Linux

Based on:
  [lldb-dev] proposed change to remove conditional WCHAR support in libedit wrapper
  https://lists.llvm.org/pipermail/lldb-dev/2021-July/016961.html

There is already setlocale in lldb/source/Core/IOHandlerCursesGUI.cpp
but that does not apply for Editline GUI editing.

Unaware how to make automated test for this, it requires pty.

Reviewed By: teemperor

Differential Revision: https://reviews.llvm.org/D105779

lldb/source/Core/IOHandlerCursesGUI.cpp

@@ -67,7 +67,6 @@
 #include <cassert>
 #include <cctype>
 #include <cerrno>
-#include <clocale>
 #include <cstdint>
 #include <cstdio>
 #include <cstring>
@@ -2627,8 +2626,6 @@ class Application {
   }
 
   void Initialize() {
-    ::setlocale(LC_ALL, "");
-    ::setlocale(LC_CTYPE, "");
     m_screen = ::newterm(nullptr, m_out, m_in);
     ::start_color();
     ::curs_set(0);

lldb/tools/driver/Driver.cpp

@@ -31,6 +31,7 @@
 #include <algorithm>
 #include <atomic>
 #include <bitset>
+#include <clocale>
 #include <csignal>
 #include <string>
 #include <thread>
@@ -867,6 +868,10 @@ static llvm::Optional<int> InitializeReproducer(llvm::StringRef argv0,
 }
 
 int main(int argc, char const *argv[]) {
+  // Editline uses for example iswprint which is dependent on LC_CTYPE.
+  std::setlocale(LC_ALL, "");
+  std::setlocale(LC_CTYPE, "");
+
   // Setup LLVM signal handlers and make sure we call llvm_shutdown() on
   // destruction.
   llvm::InitLLVM IL(argc, argv, /*InstallPipeSignalExitHandler=*/false);