[lldb] Don't cache lldb_find_python_module result

Don't cache lldb_find_python_module result as that requires you to do a
clean build after installing the dependency.

Author: JDevlieghere

lldb/cmake/modules/AddLLDB.cmake

@@ -383,7 +383,7 @@ endfunction()
 
 function(lldb_find_python_module module)
   set(MODULE_FOUND PY_${module}_FOUND)
-  if (DEFINED ${MODULE_FOUND})
+  if (${MODULE_FOUND})
     return()
   endif()
 
@@ -392,10 +392,10 @@ function(lldb_find_python_module module)
     ERROR_QUIET)
 
   if (status)
-    set(${MODULE_FOUND} OFF CACHE BOOL "Failed to find python module '${module}'")
+    set(${MODULE_FOUND} OFF PARENT_SCOPE)
     message(STATUS "Could NOT find Python module '${module}'")
   else()
-    set(${MODULE_FOUND} ON CACHE BOOL "Found python module '${module}'")
+    set(${MODULE_FOUND} ON PARENT_SCOPE)
     message(STATUS "Found Python module '${module}'")
   endif()
 endfunction()