[Exim] compile exim with "gdbm"

hi,

i try to compile exim with the "gdbm" instead of using the berkley-db,
provided by sleepycat.
but, there are two issues:
* theres no "db.h" (i copyied this one from an other distribution, but
shouldnt provide gdbm someting like this?)
* compiling this, i get an error 1:
-------------------------------
gcc -O -I/usr/local/include -o exim_dbmbuild exim_dbmbuild.c \
-lnsl -lcrypt -lgdbm
/tmp/cc9z6ErG.o: In function `main':
/tmp/cc9z6ErG.o(.text+0x2b6): undefined reference to `db_open'
collect2: ld returned 1 exit status
make[1]: *** [exim_dbmbuild] Error 1
make[1]: Leaving directory `/usr/src/exim-3.33/build-Linux-i386'
make: *** [go] Error 2
-------------------------------

yes, i runned "ldconfig", so the installed gdbm sould known to ld
as described in the exim.spec-file, it runs with gdbm...

what im doing wrong?
frank