On 16/08/2013 23:22, Francisco Ares wrote:

      26892 Illegal instruction     | $AWK -f "$ac_tmp/subs.awk" >

      31167 Illegal instruction     | $AWK -f "$tmp/subs.awk" > $tmp/out

> [...]

I have built binary packages for "sed" and "gawk", created in a machine
with the same characteristics and configuration, and emerged those to
the new machine.  Even so, the errors keep coming.

It could be an issue with faulty memory, or problem with glibc.

Often though, illegal instruction is the result of a mismatch between the host, and the target for which the binary was compiled.
This could be checked by comparing /proc/cpuinfo with your CFLAGs.