[llvm-objdump][MachO] Update check in flaky test that depends on directory path (#150674)

Earlier, function-starts.test failed when directory path contained
'_main', because objdump prints out the entire directory path, and there
is an implicit-check-not for '_main'.
There's three ways in which [function starts are printed by
llvm-objdump](https://llvm.org/docs/CommandGuide/llvm-objdump.html#cmdoption-llvm-objdump-function-starts): 

With the "addr" mode, there will be no "_main"\
With "names", it'll be printed as "_main\n"\
With "both", it'll be printed as "<addr> _main\n". 

The existing check for function-starts=addrs checks that the pattern for
"names" or "both" does not get printed. This MR changes the RUN lines to
take stdin input, so that no directory path is printed, and stray _main
strings in the directory path will not make the test fail.

0 files changed, 0 insertions, 0 deletions