[MC/ELF] - Fixed insufficient compression.s test
[MC/ELF] - Fixed insufficient compression.s test

Main problem that .debug_info
section was used to check that llvm-dwarfdump is able to decompress
data that was compressed with llvm-mc tool. This section was not compressed
actually, because consumes more space in compressed view.

I changed testcase to use .debug_str section which is one that
is really compressed. So currently test do what is probably was expected to do:
checks that "data"->llvm-mc->llvm-dwarfdump->dumps back initial "data".

Differential revision: http://reviews.llvm.org/D20466

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@270560 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm