Forum OpenACS Q&A: Re: openacs seems to install successful.but still have problem about load lib.
In short: at least ion Ubuntu, the build system has added the default optimization flag "-Wl,--as-needed" lately. This optimization removes symbols which are not needed for linking. Therefore, the symbol Ns_DbDriverInit is probably removed this way, but is is necessary for the dynamic loading in Tcl.
To fix the issue, the Debian maintainer has to add "-Wl,--no-as-needed" to the CFLAGs in the Makefile before compiling. A bug report is filed for debian.