[llvm-profdata] Weaken "malformed-ptr-to-counter-array.test" to appease arm bots

There are a number arm bots failing after r374617 landed, and I'm not
sure why. It looks a bit like the error message llvm-profdata is
expected to print to stderr isn't flushed.

Weaken the test in an attempt to appease the arm bots: if this doesn't
work, that means that llvm-profdata is actually *not failing*, and that
will be a clear indication that some logic error is actually happening.

http://lab.llvm.org:8011/builders/clang-cmake-armv7-global-isel/builds/5604/

llvm-svn: 374792