comm tests require a serial device for testing. If the test environment
isn't available the tests will return errors therefore the tests are
now disabled per default. They can be (re-)enabled by using the cmake
option BUILD_COMM_TESTS.
winpr is now always build as single library.
The build option MONOLITHIC_BUILD doesn't influence this behavior anymore.
The only exception is winpr-makecert-tool which is still build as extra
library.
This obsoletes complex_libraries for winpr.
