Default initialize enum flags to 0

... so that we don't need to do it manually, and potentially forget.
For example, this allows to do:

  my_flags flags;

  ...

  flags |= some_flag;

gdb/ChangeLog:

	* common/enum-flags.h (enum_flags::enum_flags): Initialize
	m_enum_value to 0 in default constructor.

1 files changed, 2 insertions, 1 deletions

diff --git a/gdb/common/enum-flags.h b/gdb/common/enum-flags.h
index 5b8c3ebc..e63c8a4 100644
--- a/gdb/common/enum-flags.h
+++ b/gdb/common/enum-flags.h
@@ -115,8 +115,9 @@ private:
   }
 
 public:
-  /* Allow default construction, just like raw enums.  */
+  /* Allow default construction.  */
   enum_flags ()
+    : m_enum_value ((enum_type) 0)
   {}
 
   enum_flags (const enum_flags &other)