Error while compiling Exim (directadmin custombuild) - unix

Question

I'm currently running DirectAdmin on my Debian 6.0.9 and got a message that Exim needed to be updated. So i did my regular commands:
./build update
./build versions
./build update_versions
But, whenever I run these commands, i get the following error:
In file included from tls.c:121:
tlscert-openssl.c: In function ‘asn1_time_copy’:
tlscert-openssl.c:114: warning: passing argument 2 of ‘ASN1_TIME_print’ discards qualifiers from pointer target type
/usr/include/openssl/asn1.h:1006: note: expected ‘struct ASN1_TIME *’ but argument is of type ‘const struct ASN1_TIME *’
gcc tod.c
gcc transport.c
gcc tree.c
gcc verify.c
gcc lookups/lf_quote.c
gcc lookups/lf_check_file.c
gcc lookups/lf_sqlperform.c
gcc local_scan.c
cc perl.c
gcc malware.c
gcc mime.c
gcc regex.c
gcc spam.c
gcc spool_mbox.c
gcc demime.c
gcc bmi_spam.c
gcc spf.c
gcc srs.c
gcc dcc.c
gcc dmarc.c
gcc dane.c
gcc version.c
gcc -o exim
/usr/bin/ld: cannot find -lgdbm
collect2: ld returned 1 exit status
make[1]: *** [exim] Error 1
make[1]: Leaving directory `/usr/local/directadmin/custombuild/exim-4.85/build-Linux-x86_64'
make: *** [all] Error 2
*** The make has failed, would you like to try to make again? (y,n): n
Google doesn't really help and I'm running out of ideas.

Answer 1

Credits go to tripleee
The server was missing libgdbm-dev. So after
sudo apt-get install libgdbm-dev
It was working fine.