Fix failing prettyprinter test

The failure for "p2" went unnoticed due to the pre-existing failures for
variables with similar names, like "p" and "q". This fixes the failure,
and gives the filesystem::path variables better names.

	* testsuite/libstdc++-prettyprinters/cxx17.cc: Fix expected output
	for filesystem::path. Give variables more distinctive names.

From-SVN: r267762