fix .debug_aranges parsing

Summary:
Each sequence of tuples within an entires set is terminated with (0,
0) according to the DWARF standard (see 7.20 in
http://www.dwarfstd.org/doc/DWARF4.pdf).

Reviewed By: ot, luciang

Differential Revision: D4014952

fbshipit-source-id: c4b034c94adc4a0d9b052456c02919a54a79eaf1

folly/experimental/symbolizer/Dwarf.cpp

@@ -457,7 +457,7 @@ bool Dwarf::findDebugInfoOffset(uintptr_t address,
       auto start = read<uintptr_t>(chunk);
       auto length = read<uintptr_t>(chunk);
 
-      if (start == 0) {
+      if (start == 0 && length == 0) {
         break;
       }