Style: removed unused header, other small fixes

sql/field.h

@@ -33,8 +33,6 @@
 #include "compat56.h"
 #include "sql_type.h"                           /* Type_std_attributes */
 
-#include <limits>
-
 class Send_field;
 class Copy_field;
 class Protocol;

sql/handler.cc

@@ -6559,7 +6559,7 @@ static bool create_string(MEM_ROOT *mem_root, String **s, const char *value)
   return *s == NULL;
 }
 
-static bool create_sys_trx_field_if_missing(THD *thd, const char *field_name,
+static bool create_sys_trx_field(THD *thd, const char *field_name,
                                  Alter_info *alter_info, String **s,
                                  bool integer_fields)
 {
@@ -6626,9 +6626,9 @@ bool Vers_parse_info::add_versioning_info(
       period_for_system_time.start || period_for_system_time.end)
     return false;
 
-  return create_sys_trx_field_if_missing(thd, "sys_trx_start", alter_info,
+  return create_sys_trx_field(thd, "sys_trx_start", alter_info,
                               &generated_as_row.start, integer_fields) ||
-         create_sys_trx_field_if_missing(thd, "sys_trx_end", alter_info,
+         create_sys_trx_field(thd, "sys_trx_end", alter_info,
                               &generated_as_row.end, integer_fields) ||
          create_string(thd->mem_root, &period_for_system_time.start,
                        "sys_trx_start") ||
@@ -6732,4 +6732,3 @@ bool Vers_parse_info::check(THD *thd, Alter_info *alter_info, bool integer_field
 
   return r; // false means no error
 }
-