Using gawk as an example:
1. The configuration step complains:
checking for C compiler default output file name... configure: error: C
compiler cannot create executables See `config.log' for more details.

2. .work.log says:
.> /export/home/pkgsrc/lang/gawk/work/.gcc/bin/gcc -O
-I/export/home/pkgsrc/lan g/gawk/work/.buildlink/include
-L/export/home/pkgsrc/lang/gawk/work/.buildlink/l ib -Wl,-R/usr/pkg/lib
conftest.c -lintl -liconv

3. I  copy libiconv.so from the package lib dir into the .buildlink lib
directory and rebuild. Lo and Behold, the build is successful.

I thought buildlink would have done a symbolic lnk of libiconv.so.