WL#5030: Split and remove mysql_priv.h

This patch:

- Moves all definitions from the mysql_priv.h file into
  header files for the component where the variable is
  defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h

sql/sql_bitmap.h

@@ -19,6 +19,9 @@
   also be able to use 32 or 64 bits bitmaps very efficiently
 */
 
+#ifndef SQL_BITMAP_INCLUDED
+#define SQL_BITMAP_INCLUDED
+
 #include <my_bitmap.h>
 
 template <uint default_width> class Bitmap
@@ -138,3 +141,5 @@ public:
   ulonglong to_ulonglong() const { return map; }
 };
 
+
+#endif /* SQL_BITMAP_INCLUDED */