[llvm] [llvm-strings] Use small buffer instead of reading whole file (PR #163073)

[James Henderson via llvm-commits]

================
@@ -0,0 +1,13 @@
+## Show that a file that opens but cannot be read is reported on stderr, and
+## that processing continues with the remaining inputs. A directory can be
+## opened for reading on POSIX systems, but reading from it fails with
+## EISDIR. On Windows opening the directory fails instead, so the read error
+## path is not reachable this way.
+# UNSUPPORTED: system-windows
----------------
jh7370 wrote:

You might want to look at other tools that try to open a directory as a file in a test. I have this memory that on some platforms, directories can be read from, which would presumably result in a different behaviour. We probably just want an UNSUPPORTED directive for the relevant systems, in addition to Windows.

https://github.com/llvm/llvm-project/pull/163073