Split ws_regex_matches() into two functions with better semantics
and remove the WS_REGEX_ZERO_TERMINATED symbol.
ws_regex_matches() matches zero terminated strings.
ws_regex_matches_length() matches a string length in code units.
The type ssize_t is not available on Windows. Because this is
used in the public API we must provide a definition for it.
To avoid having to add a header to fix this use a size_t in
the API instead, and assign SIZE_MAX to represent a null
terminated string.
Add @file markers for remaining non-dissector
files that contain functions exported with
WS_DLL_PUBLIC so that Doxygen will
generate documentation for them.