[llvm] [lit] Add an option to read an xfail list from a file (PR #163959)

[David Spickett via llvm-commits]

================
@@ -346,6 +346,10 @@ The timing data is stored in the `test_exec_root` in a file named
 
     LIT_XFAIL="affinity/kmp-hw-subset.c;libomptarget :: x86_64-pc-linux-gnu :: offloading/memory_manager.cpp"
 
+.. option:: --xfail-from-file PATH
+
+  Read a line separated list of tests from a file to be used by :option:`--xfail`.
----------------
DavidSpickett wrote:

Maybe "line separated" is a standard term but I don't know if it means:
```
thing

thing
```
Or:
```
thing\nthing
```
I guess the latter?

Or in other words: one test name/pattern per line.

https://github.com/llvm/llvm-project/pull/163959