bug: solaris build does not use --prefix properly

Hello,

I believe I have found a bug in the solaris build of aspell. To repro:

- untar aspell (e.g. 0.60.3)
- ./configure --prefix=/some/nonstandard/dir
- make
- make install
- cd /some/nonstandard/dir/bin
- ./aspell dump config dict-dir

result:
/usr/local/lib/aspell-0.60

expected:
/some/nonstandard/dir/aspell-0.60


Notes:
- linux (redhat ES3) does not have this problem.
- I tried also setting secondary directories with configure (e.g. 
exec-prefix, etc.), which are supposed to inherit from prefix, but this 
did not fix the issue.
- appears to be introduced somewhere in the autoconf/make phase, but I 
don't know enough about those things to figure it out.

I looked through the aspell-devel and aspell-user archives for similar 
issues but did not find any. Apologies if this is a previously 
discussed issue.

Thanks,
Tyler