Revert r270977 ([llvm-mc] - Teach llvm-mc to generate zlib styled compression sections.)

It broke buildbot:
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/13585/steps/build/logs/stdio

Initial commit message:
[llvm-mc] - Teach llvm-mc to generate zlib styled compression sections.

This patch is strongly based on previously reverted D20331.
(because of gnuutils < 2.26 does not support compressed debug sections in non zlib-gnu style)

Difference that this patch supports both zlib and zlib-gnu styles.

-compress-debug-sections option now supports next values:

-compress-debug-sections=zlib-gnu
-compress-debug-sections=zlib
-compress-debug-sections=none
Previously specifying -compress-debug-sections enabled zlib-gnu compression,
so anyone can put "-compress-debug-sections=zlib-gnu" to restore the behavior
that was before this patch for case when compression was enabled.

Differential revision: http://reviews.llvm.org/D20676

llvm-svn: 270978
diff --git a/llvm/lib/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index 2f7f8df..3be8af8 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -71,7 +71,7 @@
     TmpAsmInfo->setUseIntegratedAssembler(false);
 
   if (Options.CompressDebugSections)
-    TmpAsmInfo->setCompressDebugSections(DebugCompressionType::DCT_ZlibGnu);
+    TmpAsmInfo->setCompressDebugSections(true);
 
   AsmInfo = TmpAsmInfo;
 }