[Darwin, testsuite] Address PR91087 - XFAIL parts of pr16855.C.

[Darwin, testsuite] Address PR91087 - XFAIL parts of pr16855.C.

The testcase is failing to instrument part of the source because of a bug
in the ordering of static DTORs.  It seems unlikely that this is generically
fixable in the toolchain (and given that it's likely to be a dynamic loader
change would not be expected to be applied retrospectively to OS versions
that are out of support).  To avoid the testsuite noise, xfail the count lines
that don't match (we can adjust the xfails as/when the upstream bug is fixed).

dejagnu xfails do not seem to work when embedded in a line like:
  ~Test (void) { .... /* count(1) { xfail ... } */ }
the closing brace seems to confuse the parser.  The solution is to exapnd the
text onto three lines.

2019-07-25  Iain Sandoe  <iain@sandoe.co.uk>

	PR gcov-profile/91087
	* g++.dg/gcov/pr16855.C: Xfail the count lines for the DTORs and the
	"final" line for the failure summaries.  Adjust source layout so that
	dejagnu xfail expressions work.

From-SVN: r273809