nuudlman/llvm: llvm/test/tools/llvm-strings/stdin-filename.test

Compiler projects using llvm

## Show that --print-file-name works when the input is standard input.

RUN: echo abcd | llvm-strings -f - | FileCheck %s
RUN: echo abcd | llvm-strings -f | FileCheck %s
RUN: echo abcd | llvm-strings --print-file-name - | FileCheck %s
RUN: echo abcd | llvm-strings --print-file-name | FileCheck %s
CHECK: {standard input}: abcd