Make abuse build properly with superenv on OS X 10.8

Should fix #18.

* abuse is dependent on `sdl_mixer`, but this wasn't listed. A few build dependencies were also missing, which caused the build to fail without `--env=std`.
* The bootstrap script tries to detect scripts named `automake-1.x`, but only does so for `x` between 5 and 11 inclusive. I replaced this with a call to `seq` so that anything up to 99 will work.
* autotools complains about an obsolete `AM_CONFIG_HEADER` macro. A simple search-and-replace to `AC_CONFIG_HEADERS`, as the error message advises, fixes this.