[lit] Improve readability of failing scripts.
- This only applies to scripts executed by the _internal_ shell script
interpreter.
- This patch reworks the log to look more like a shell transcript, and be less
verbose (but in the interest of calling attention to the important parts).
Here is an example of the new format, for commands with/without failures and
with/without output:
```
$ true
$ echo hi
hi
$ false
note: command had no output on stdout or stderr
error: command failed with exit status 1
```
llvm-svn: 271610
diff --git a/llvm/utils/lit/tests/shtest-format.py b/llvm/utils/lit/tests/shtest-format.py
index 39b0e9c..20884f8 100644
--- a/llvm/utils/lit/tests/shtest-format.py
+++ b/llvm/utils/lit/tests/shtest-format.py
@@ -39,9 +39,8 @@
#
# CHECK: Command Output (stdout):
# CHECK-NEXT: --
-# CHECK-NEXT: Command 0: "printf"
-# CHECK-NEXT: Command 0 Result: 0
-# CHECK-NEXT: Command 0 Output:
+# CHECK-NEXT: $ "printf"
+# CHECK-NEXT: # command output:
# CHECK-NEXT: line 1: failed test output on stdout
# CHECK-NEXT: line 2: failed test output on stdout