Revert "[Decompression] Fail gracefully when out of memory"

This reverts commit r312526.

Revert "Fix test/DebugInfo/dwarfdump-decompression-invalid-size.test"

This reverts commit r312527.

It causes an ASan failure:
http://lab.llvm.org:8080/green/job/clang-stage2-cmake-RgSan_check/4150

llvm-svn: 312582