tests: Add gcov support for sparc64 qtest

m48t59-test is individually being executed for sparc and sparc64, so add
the gcov source file for sparc64 as well.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

tests/Makefile

@@ -60,6 +60,7 @@ gcov-files-i386-y += i386-softmmu/hw/mc146818rtc.c
 check-qtest-sparc-y = tests/m48t59-test$(EXESUF)
 check-qtest-sparc64-y = tests/m48t59-test$(EXESUF)
 gcov-files-sparc-y += hw/m48t59.c
+gcov-files-sparc64-y += hw/m48t59.c
 check-qtest-arm-y = tests/tmp105-test$(EXESUF)
 gcov-files-arm-y += hw/tmp105.c