This switches the current hello_world to be hello_world-policy now,
and hello_world is simplified to use the __default policy without any
explicit policy of its own.
Using the default policy means it relies on the system tls library to
validate the tls connections using system trust arrangements, that won't
work in cases where the configured tls library does not have its own trust
store.
Although many of the examples must be run from the example directory as
cwd, everyone getting started probably wants to try the examples, cmake
knows how to do it, so let's enable it by default.
There's no problem for library build, also with LWS_WITH_MINIMAL_EXAMPLES,
but after install at least on OSX, there are problems finding the installed
lws include dir (concealed on most platforms by the path being in the
default search list for the toolchain), and the references in the lws
includes to the tls includes meaning that explicit paths for that must be
available at consuming cmakes.
This patch enhances the cmake config installed by lws to deal with adding
the lws include paths to CMAKE_REQUIRED_INCLUDES and include_directories,
so it can be found before the target is introduced.
The tls include is passed back up the CMakeLists layers and the lws targets
marked with target_include_directories(PUBLIC) with them, so they are
understood as needed by consumers.
More boilerplate is moved out of the example consuming cmakes.
After this, on machines with previous installs of older lws, you may have to
clean out the cmake install path, that is usually something like
/usr/local/lib/cmake/libwebsockets/*
before make installing lws and putting the latest content in there.
