Bug#724186: frei0r: fix for new automake

[Rebecca N. Palmer]

The only change _required_ now is adding -i to autoreconf (in 
debian/rules), but it seemed a good idea to also fix the deprecation 
warnings (copied below) before they become errors in a future version.

configure.ac:8: warning: AM_INIT_AUTOMAKE: two- and three-arguments 
forms are deprecated.  For more info, see:
configure.ac:8: 
http://www.gnu.org/software/automake/manual/automake.html#Modernize-AM_005fINIT_005fAUTOMAKE-invocation
configure.ac:12: installing './compile'
src/Makefile.am:72: warning: source file 'filter/3dflippo/3dflippo.c' is 
in a subdirectory,
src/Makefile.am:72: but option 'subdir-objects' is disabled
automake: warning: possible forward-incompatibility.
automake: At least a source file is in a subdirectory, but the 
'subdir-objects'
automake: automake option hasn't been enabled.  For now, the 
corresponding output
automake: object file(s) will be placed in the top-level directory. 
However,
automake: this behaviour will change in future Automake versions: they will
automake: unconditionally cause object files to be placed in the same 
subdirectory
automake: of the corresponding sources.
automake: You are advised to start using 'subdir-objects' option 
throughout your
automake: project, to avoid future incompatibilities.