* cdemo/foo1.c: renamed to foo.c
* libltdl/ltdl.c: eliminated lt_dltype, in presym_open():
search for @PROGRAM@ if filename == 0, in lt_dlopen():
fixed bug for filename == 0
* libltdl/ltdl.h: use __P macro for lt_dlmalloc/free
* libtool.m4: new macro AC_LIBTOOL_DLOPEN: checks for dlopen
and dlopen(NULL) support
* ltconfig.in: added new variables dlopen and dlopen_self,
--enable-dlopen[-self] flags for AC_LIBTOOL_DLOPEN
* ltmain.in: use dlopen[_self], dlpreopen files if there's no
dlopen support, build lt_preloaded_symbols only if
-dl[pre]open was used, include program symbols if -export-dynamic
was specified and there's no dlopen(NULL) support
* mdemo/configure.in: use AC_LIBTOOL_DLOPEN
* mdemo/main.c: demonstrate lt_dlopen(0)