Split item->flags into base_flags and with_flags

This was done to simplify copying of with_* flags

Other things:
- Changed Flags to C++ enums, which enables gdb to print
  out bit values for the flags. This also enables compiler
  errors if one tries to manipulate a non existing bit in
  a variable.
- Added set_maybe_null() as a shortcut as setting the
  MAYBE_NULL flags was used in a LOT of places.
- Renamed PARAM flag to SP_VAR to ensure it's not confused with persistent
  statement parameters.

1 files changed, 1 insertions, 1 deletions

diff --git a/plugin/func_test/plugin.cc b/plugin/func_test/plugin.cc
index 827c627dece..5e1f1a66fa2 100644
--- a/plugin/func_test/plugin.cc
+++ b/plugin/func_test/plugin.cc
@@ -32,7 +32,7 @@ public:
   bool fix_length_and_dec()
   {
     max_length= MAX_FIELD_NAME * system_charset_info->mbmaxlen;
-    flags|= ITEM_FLAG_MAYBE_NULL;
+    set_maybe_null();
     return false;
   }
   const char *func_name() const { return "sysconst_test"; }