Removed some alias warnings

Fixed alias bug when compiling with gcc 4.2.4 that caused subselect.test to fail

sql/item.cc:
  Removed alias warnings by changing type from char * to const char*
sql/item.h:
  Removed alias warnings by changing type from char * to const char*
sql/item_subselect.cc:
  Fixed alias bug when compiling with gcc 4.2.4 that caused subselect.test to fail
sql/sql_string.h:
  Removed alias warnings by changing type from char * to const char*
storage/heap/hp_test2.c:
  Removed SAFEMALLOC to get rid of compiler error
  Fixed test case as we can't anymore use heap_rlast() on a HASH key entry.

1 files changed, 3 insertions, 2 deletions

diff --git a/sql/sql_string.h b/sql/sql_string.h
index 92a896c1cae..e4cce7b5527 100644
--- a/sql/sql_string.h
+++ b/sql/sql_string.h
@@ -457,8 +457,9 @@ public:
   }
 };
 
-static inline bool check_if_only_end_space(CHARSET_INFO *cs, char *str, 
-                                           char *end)
+static inline bool check_if_only_end_space(CHARSET_INFO *cs,
+                                           const char *str, 
+                                           const char *end)
 {
   return str+ cs->cset->scan(cs, str, end, MY_SEQ_SPACES) == end;
 }