Features enable code coverage collecting using the gcov tool. The
resulting reports can then be post-processed by lcov or similar tools.
[ChangeLog][CMake][Coverage] Added the coverage configuration argument.
The only supported coverage tool at the moment is gcov. The argument
requires Qt is built in Debug otherwise setting the argument leads to
the configuration error. Typical usage:
<...>/configure -developer-build -coverage gcov
Task-number: QTBUG-86223
Change-Id: I39b2061f544997a7c4fe6f4d135c0ab447f15a17
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>