Capture only coverage data for the current project in the first place, instead...

Capture only coverage data for the current project in the first place, instead of extracting it from all coverage data in a second step. This seems to be needed as extraction spuriously might fail in some cases.

cmake/Makefile.coverage.in

@@ -19,8 +19,5 @@
 coverage:
 	rm -f `find . -name "*\.gcda"`
 	make test
-	lcov --capture --directory . --output-file coverage_all.info
-	#lcov capture also includes external stuff like glibc, boost etc.
-	#only extract the reports for this project
-	lcov --extract coverage_all.info "@CMAKE_SOURCE_DIR@*" -o coverage.info
+	lcov --capture --directory . --output-file coverage.info --no-external --base-directory "@CMAKE_SOURCE_DIR@"
 	genhtml coverage.info --output-directory coverage_html