Make package breaks due to empty MYDOCS variable.

Fix: # cat /usr/ports/databases/qdbm/files/patch-Makefile.in
How-To-Repeat: % cd /usr/ports/databases/qdbm
% make NOPORTDOCS=yes package
===>  Installing for qdbm-1.8.75
===>   qdbm-1.8.75 depends on shared library: iconv.3 - found
===>   Generating temporary packing list
===>  Checking if databases/qdbm already installed
mkdir -p /usr/local/include
cd . && cp -Rf depot.h curia.h relic.h hovel.h cabin.h villa.h vista.h odeum.h /usr/local/include
mkdir -p /usr/local/lib
cp -Rf libqdbm.a libqdbm.so.14.11.0 libqdbm.so.14 libqdbm.so /usr/local/lib
mkdir -p /usr/local/bin
cp -Rf dpmgr dptest dptsv crmgr crtest crtsv rlmgr rltest hvmgr hvtest  cbtest cbcodec vlmgr vltest vltsv odmgr odtest odidx qmttest /usr/local/bin
mkdir -p /usr/local/man/man1
cd ./man && cp -Rf dpmgr.1 dptest.1 dptsv.1 crmgr.1 crtest.1 crtsv.1 rlmgr.1 rltest.1 hvmgr.1 hvtest.1  cbtest.1 cbcodec.1 vlmgr.1 vltest.1 vltsv.1 odmgr.1 odtest.1 odidx.1 qmttest.1 /usr/local/man/man1
mkdir -p /usr/local/man/man3
cd ./man && cp -Rf qdbm.3 depot.3 dpopen.3 curia.3 cropen.3 relic.3 hovel.3  cabin.3 villa.3 vlopen.3 vista.3 odeum.3 odopen.3 /usr/local/man/man3
mkdir -p /usr/local/share/doc/qdbm
cd . && cp -Rf  /usr/local/share/doc/qdbm
usage: cp [-R [-H | -L | -P]] [-f | -i | -n] [-lpv] source_file target_file
       cp [-R [-H | -L | -P]] [-f | -i | -n] [-lpv] source_file ... target_directory
*** Error code 64

Stop in /usr/ports/works/usr/ports/databases/qdbm/work/qdbm-1.8.75.
*** Error code 1

Stop in /usr/ports/databases/qdbm.