autotools revamp:

autotools revamp:
- rebuild aclocal.m4 with current libtool support, and regen ltmain.sh
  as well
- rename all local macros to FR_* instead of AC_*
- require autoconf 2.53 or better, for better recursion support
- rerun autoconf
- update Debian build depends, and fix the way we're declaring our
  architecture to autoconf
- always use $(LIBTOOL) instead of $(CC) for compiling
- always link with $(LIBTOOL) --mode=link $(CC), not $(LD)
- break down the static/dynamic divide in the Makefiles (leave this to
  libtool)
- don't pass -module for objects that aren't freeradius modules
- always depend on .la targets, not .a
- declare modules' dependency on libradius.la
- link libeap.la and rlm_sql.la against libltdl
- declare interdependencies between rlm_eap submodules