testsuite: Remove duplicate -lgcov [PR114034]

testsuite: Remove duplicate -lgcov [PR114034]

Duplicate library entries now cause linker warnings with newer linker
versions on Darwin which leads to these tests regressing.  The library
is already added by the test flags so there is no need to put an extra
one in the options.

	PR testsuite/114034

gcc/testsuite/ChangeLog:

	* g++.dg/gcov/gcov-dump-1.C: Remove extra -lgcov.
	* g++.dg/gcov/gcov-dump-2.C: Likewise.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
(cherry picked from commit 799a056cf804f433ce0050a5a6bf900f7a01ecb1)