* acinclude.m4 (GNUPG_CHECK_TYPEDEF): Remove.  We can just use
AC_CHECK_TYPES.
(GNUPG_CHECK_GNUMAKE): Remove.  It may build with other Make.
(GNUPG_SYS_LIBTOOL_CYGWIN32): Remove.  Now, it's done by LT_INIT.
(TYPE_SOCKLEN_T): Remove.  Now, we use gl_TYPE_SOCKLEN_T.