Fixed compile failure when we don't use system zlib

Fixed crash when setting query_cache_type to 0.

client/Makefile.am:
  Added zlib include (needed by checksum.c)
sql/set_var.cc:
  Updated call to disable_query_cache()
sql/sql_cache.cc:
  Don't give warning if we start mysqld with --query_cache_type=0 --query_cache-size=0
  Fixed crash when setting query_cache_type to 0 (we shouldn't call query_cache.disable_query_cache() when there is no current_thd)
sql/sql_cache.h:
  Added THD to disable_query_cache()

client/Makefile.am

@@ -24,6 +24,7 @@ endif
 INCLUDES =			-I$(top_builddir)/include \
 				-I$(top_srcdir)/include \
 				-I$(top_srcdir)/regex \
+				@ZLIB_INCLUDES@ \
                                 $(openssl_includes)
 
 LIBS =				@CLIENT_LIBS@

sql/set_var.cc

@@ -1288,7 +1288,7 @@ static void fix_query_cache_type(THD *thd, enum_var_type type)
       fix_query_cache_size(thd, type);
     }
     else if (global_system_variables.query_cache_type == 0)
-      query_cache.disable_query_cache();
+      query_cache.disable_query_cache(thd);
   }
 }
 

sql/sql_cache.cc

@@ -1277,7 +1277,8 @@ ulong Query_cache::resize(ulong query_cache_size_arg)
 
   if (global_system_variables.query_cache_type == 0)
   {
-    my_error(ER_QUERY_CACHE_IS_DISABLED, MYF(0));
+    if (query_cache_size_arg != 0)
+      my_error(ER_QUERY_CACHE_IS_DISABLED, MYF(0));
     DBUG_RETURN(0);
   }
 
@@ -2318,7 +2319,7 @@ void Query_cache::destroy()
 }
 
 
-void Query_cache::disable_query_cache(void)
+void Query_cache::disable_query_cache(THD *thd)
 {
   m_cache_status= DISABLE_REQUEST;
   /*
@@ -2326,7 +2327,7 @@ void Query_cache::disable_query_cache(void)
     try_lock(TRY) will exit immediately if there is lock.
     unlock() should free block.
   */
-  if (m_requests_in_progress == 0 && !try_lock(current_thd, TRY))
+  if (m_requests_in_progress == 0 && !try_lock(thd, TRY))
     unlock();
 }
 
@@ -2346,14 +2347,16 @@ void Query_cache::init()
   initialized = 1;
   query_state_map= default_charset_info->state_map;
   /*
-    If we explicitly turn off query cache from the command line query cache will
-    be disabled for the reminder of the server life time. This is because we
-    want to avoid locking the QC specific mutex if query cache isn't going to
-    be used.
+    If we explicitly turn off query cache from the command line query
+    cache will be disabled for the reminder of the server life
+    time. This is because we want to avoid locking the QC specific
+    mutex if query cache isn't going to be used.
   */
   if (global_system_variables.query_cache_type == 0)
-    query_cache.disable_query_cache();
-
+  {
+    free_cache();
+    m_cache_status= DISABLED;
+  }
   DBUG_VOID_RETURN;
 }
 

sql/sql_cache.h

@@ -499,7 +499,7 @@ protected:
   void lock_and_suspend(void);
   void unlock(void);
 
-  void disable_query_cache(void);
+  void disable_query_cache(THD *thd);
 };
 
 extern Query_cache query_cache;