Fix DW_FORM_strp parsing

[jankratochvil]

Summary

Testing on Fedora 26 x86_64. This patch has no effect on the LLDB testsuite.
With my later DWZ patch applied I would get the following error without this patch:

59	          "{0x%8.8x}: invalid abbreviation code %u, please file a bug and "
60	          "attach the file at the start of this error message",
61	          m_offset, (unsigned)abbr_idx);

Also I find it somehow obvious. Sorry for no extra testcase.

[clayborg]

Yikes, I don't see how this was working at all, but it has been that way for a while? Good catch.

lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp

for (i = 0; i < numAttributes; ++i) {
           case DW_FORM_indirect:
             form_is_indirect = true;
             form = debug_info_data.GetULEB128(&offset);
             break;
 
           case DW_FORM_strp:
           case DW_FORM_sec_offset:
             if (cu->IsDWARF64())
-              debug_info_data.GetU64(offset_ptr);
+              debug_info_data.GetU64(&offset);
             else
-              debug_info_data.GetU32(offset_ptr);
+              debug_info_data.GetU32(&offset);
             break;
 
           default:
             *offset_ptr = m_offset;
             return false;
           }
           offset += form_size;
 
if (abbr_idx) {
               case DW_FORM_indirect:
                 form = debug_info_data.GetULEB128(&offset);
                 form_is_indirect = true;
                 break;
 
               case DW_FORM_strp:
               case DW_FORM_sec_offset:
                 if (cu->IsDWARF64())
-                  debug_info_data.GetU64(offset_ptr);
+                  debug_info_data.GetU64(&offset);
                 else
-                  debug_info_data.GetU32(offset_ptr);
+                  debug_info_data.GetU32(&offset);
                 break;
 
               default:
                 *offset_ptr = offset;
                 return false;
               }
 
               offset += form_size;