Mark wsutil's includes SYSTEM PRIVATE. This exposed a lot of targets
that were indirectly picking up include paths via the wsutil target, so
add direct includes where needed. The G.722 and G.726 codecs were
implicilty including tiffio.h; find it explicitly instead.
Mark some of wsutil's libraries PRIVATE, but leave commonly-used ones
PUBLIC.
Ping #17477.
Calling cmake with -DENABLE_VLD=ON when building with Visual Studio,
results in debug configuration being linked to Visual Leak Detector.
By default, Visual Leak Detector outputs the leak summary to Visual
Studio debug window. When ENABLE_VLD is active, VLD is linked to all
wireshark libraries and executables.
The distinction between the different kinds of capture utility
may not warrant a special subfolfer for each, and sometimes the
distinction is not be clear or some functions could stradle
multiple "categories" (like capture_ifinfo.[ch]).
Simplify by having only a generic 'capture' subfolder. The
separate CMake libraries are kept as a way to reuse object code
efficiently.