lit: Add '-a' option to display commands+output of all tests
lit: Add '-a' option to display commands+output of all tests

The existing -v option only displays commands and outputs for failed
tests, the newly introduced -a displays it for all executed tests.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@251806 91177308-0d34-0410-b5e6-96231b3b80d8

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