Versioning is for libraries. Modules are not libraries; no code is linked
against them.
Libtool makes sure the modules can be opened by dlopen(). That is already
true for ELF format, but other file formats may need special processing.
This fixes loading modules compiled with a C++ compiler. Remote thandle
type, it's unused. Use tintptr for module data. Don't cast pointers to
long, they won't fit on Win64.
libdir is for shared and static libraries. Some xrdp libraries are loaded
dynamically from a non-standard directory, so they are used like modules.
Having separate libdir and moduledir would eventually allow to separate
dynamically loaded modules from shared libraries.
AM_CPPFLAGS is for flags passed to the preprocessor, such as defines and
includes. AM_CFLAGS is for flags affecting the compiler, such as debug
and optimization settings.
INCLUDES is an obsolete name. Users can pass INCLUDES and break
compilation. AM_CPPFLAGS is more explicit that the flags come from
Automake and should not be overridden.