[lldb][windows] add a warning if CMake's version is inferior to 3.30 (llvm#164346)

llvm#140443 makes use of the CMake
variable `Python3_EXECUTABLE_DEBUG`, which was introduced in CMake
version 3.30. On systems with an inferior version of cmake, the lit
tests will try to run with an empty `config.python_executable`.

This PR adds a warning and falls back to using `Python3_EXECUTABLE` if
the CMake version is less than `3.30`.

Author: charles-zablit

lldb/test/API/CMakeLists.txt

@@ -140,7 +140,12 @@ if(CMAKE_HOST_APPLE)
 endif()
 
 if(WIN32 AND CMAKE_BUILD_TYPE STREQUAL Debug)
-  set(LLDB_PYTHON_API_TEST_EXECUTABLE "${Python3_EXECUTABLE_DEBUG}")
+  if(${CMAKE_VERSION} VERSION_LESS "3.30")
+    message(WARNING "CMake version is inferior to 3.30. Some lldb tests will fail.")
+    set(LLDB_PYTHON_API_TEST_EXECUTABLE "${Python3_EXECUTABLE}")
+  else()
+    set(LLDB_PYTHON_API_TEST_EXECUTABLE "${Python3_EXECUTABLE_DEBUG}")
+  endif()
 else()
   set(LLDB_PYTHON_API_TEST_EXECUTABLE "${Python3_EXECUTABLE}")
 endif()