[lib/Object] - Minor API update for llvm::Decompressor.

I revisited Decompressor API (issue with it was triggered during D32865 review)
and found it is probably provides more then we really need.

Issue was about next method's signature:

Error decompress(SmallString<32> &Out);
It is too strict. At first I wanted to change it to decompress(SmallVectorImpl<char> &Out),
but then found it is still not flexible because sticks to SmallVector.

During reviews was suggested to use templating to simplify code. Patch do that.

Differential revision: https://reviews.llvm.org/D33200

llvm-svn: 303331
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index 61e75a2..3dc1ec5 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -979,7 +979,7 @@
     return Decompressor.takeError();
 
   SmallString<32> Out;
-  if (auto Err = Decompressor->decompress(Out))
+  if (auto Err = Decompressor->resizeAndDecompress(Out))
     return Err;
 
   UncompressedSections.emplace_back(std::move(Out));