[llvm-opt-report] Improve error handling
[llvm-opt-report] Improve error handling

* std::move the error extracted from the parsing creation to avoid asserts
* print a newline after the error message
* create the parser from the metadata

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@371895 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm