Solve a linkage problem with "libmysqld" on several Solaris platforms:

a multiple definition of 'THD::clear_error()' in (at least)
libmysqld.a(lib_sql.o) and libmysqld.a(libfederated_a-ha_federated.o).

Patch provided by Ramil Kalimullin.

libmysqld/lib_sql.cc

@@ -756,12 +756,6 @@ void THD::clear_data_list()
   cur_data= 0;
 }
 
-void THD::clear_error()
-{
-  if (main_da.is_error())
-    main_da.reset_diagnostics_area();
-}
-
 static char *dup_str_aux(MEM_ROOT *root, const char *from, uint length,
 			 CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
 {

sql/sql_class.h

@@ -2089,7 +2089,6 @@ public:
   void add_changed_table(const char *key, long key_length);
   CHANGED_TABLE_LIST * changed_table_dup(const char *key, long key_length);
   int send_explain_fields(select_result *result);
-#ifndef EMBEDDED_LIBRARY
   /**
     Clear the current error, if any.
     We do not clear is_fatal_error or is_fatal_sub_stmt_error since we
@@ -2105,9 +2104,9 @@ public:
     is_slave_error= 0;
     DBUG_VOID_RETURN;
   }
+#ifndef EMBEDDED_LIBRARY
   inline bool vio_ok() const { return net.vio != 0; }
 #else
-  void clear_error();
   inline bool vio_ok() const { return true; }
 #endif
   /**