unittests: fix -Wnarrowing build errors

src/common/dwarf/dwarf2diehandler.cc

 // Copyright (c) 2010 Google Inc. All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
@@ skipping 149 matching lines @@
                                               uint64 data) {
   HandlerStack &current = die_handlers_.top();
   // This had better be an attribute of the DIE we were meant to handle.
   assert(offset == current.offset_);
   current.handler_->ProcessAttributeReference(attr, form, data);
 }
 
 void DIEDispatcher::ProcessAttributeBuffer(uint64 offset,
                                            enum DwarfAttribute attr,
                                            enum DwarfForm form,
-                                           const char* data,
+                                           const uint8_t *data,
                                            uint64 len) {
   HandlerStack &current = die_handlers_.top();
   // This had better be an attribute of the DIE we were meant to handle.
   assert(offset == current.offset_);
   current.handler_->ProcessAttributeBuffer(attr, form, data, len);
 }
 
 void DIEDispatcher::ProcessAttributeString(uint64 offset,
                                            enum DwarfAttribute attr,
                                            enum DwarfForm form,
                                            const string& data) {
   HandlerStack &current = die_handlers_.top();
   // This had better be an attribute of the DIE we were meant to handle.
   assert(offset == current.offset_);
   current.handler_->ProcessAttributeString(attr, form, data);
 }
 
 void DIEDispatcher::ProcessAttributeSignature(uint64 offset,
                                               enum DwarfAttribute attr,
                                               enum DwarfForm form,
                                               uint64 signature) {
   HandlerStack &current = die_handlers_.top();
   // This had better be an attribute of the DIE we were meant to handle.
   assert(offset == current.offset_);
   current.handler_->ProcessAttributeSignature(attr, form, signature);
 }
 
 } // namespace dwarf2reader