Use zlib to uncompress debug sections in DWARF parser.

This makes llvm-dwarfdump and llvm-symbolizer understand
debug info sections compressed by ld.gold linker.

llvm-svn: 180088
diff --git a/llvm/lib/DebugInfo/DWARFContext.h b/llvm/lib/DebugInfo/DWARFContext.h
index 37b2729..78c18e6 100644
--- a/llvm/lib/DebugInfo/DWARFContext.h
+++ b/llvm/lib/DebugInfo/DWARFContext.h
@@ -161,8 +161,11 @@
   StringRef RangeDWOSection;
   StringRef AddrSection;
 
+  SmallVector<MemoryBuffer*, 4> UncompressedSections;
+
 public:
   DWARFContextInMemory(object::ObjectFile *);
+  ~DWARFContextInMemory();
   virtual bool isLittleEndian() const { return IsLittleEndian; }
   virtual uint8_t getAddressSize() const { return AddressSize; }
   virtual const RelocAddrMap &infoRelocMap() const { return InfoRelocMap; }