[lldb] check python extension debug suffix on Win

ae389b2 relies on
LLDB_PYTHON_EXT_SUFFIX of Python3_EXECUTABLE for naming the result lldb
python lib.

Debug python is used in Debug LLDB on Windows, so the result lib name
requires "_d". LLDB_PYTHON_EXT_SUFFIX doesn't start with "_d" if
Python3_EXECUTABLE wasn't set to Debug executable explicitly. Perhaps a
better solution can be found after solving "debug python executable is
not currently handled" issue
(https://gitlab.kitware.com/cmake/cmake/-/issues/25874#note_1506658).

Author: amordo

lldb/CMakeLists.txt

@@ -75,6 +75,12 @@ if (LLDB_ENABLE_PYTHON)
       endif()
     endif()
   endforeach()
+  if(WIN32 AND CMAKE_BUILD_TYPE STREQUAL Debug)
+    string(SUBSTRING ${LLDB_PYTHON_EXT_SUFFIX} 0 2 FIRST_2_CHARS)
+    if(NOT FIRST_2_CHARS STREQUAL "_d")
+      set(LLDB_PYTHON_EXT_SUFFIX "_d${LLDB_PYTHON_EXT_SUFFIX}")
+    endif()
+  endif()
 endif ()
 
 if (LLDB_ENABLE_LUA)