remove ir_get_heap_used_bytes() API

The API is not really used, has nothing to do with compilers and uses
glibc/linux/windows specific extensions.
fix missing dependencies in Makefile
some cleanups
get rid of unnecessary be_spiller_t struct
cleanup, use C99
improve docu
add some overflow behaviour to tarval float to int conversions
perform float2int bitcast without expensive string conversions
no need to set tarval output modes in ia32 backend
remove per-mode output settings from tarval module

The new design simply lets you specify hex or not in tarval_snprintf.
This is way simpler than the previous machinery and enough for all users in
libfirm.
reformat ir_graph struct
use tarval_shX_unsigned where possible
change modulo_shift backend_param representation
Remove unused mode_is_dataM().
improve documentation on mode_b
disallow Muxb and Cmp(mode_b, mode_b).

We couldn't generate sensible code for them anyway.
get rid of mode_is_datab()

Most uses in the backend should be mode_is_data() the few remaining uses
can compare with mode_b explicitely.
cleanup, use C99
cleanup, use C99
add some proper switchs to tarval_div,tarval_mod,tarval_divmod