Your libc references have that SYSVABI_1.3 tag, which mine done. My Solaris 9 is a bit older. I have no idea what the problem is.
I've run into this exact issue before, as well.
Only, on Solaris 8 servers, and the offending modules being mod_mime_magic and mod_vhost_alias. I do enable-modules=most and enable-shared=max, with mod_ssl enabled shared as well.
Of course, since I don't use either of the aforementioned 2 modules in my config, simply removing them from httpd.conf "cures" the error... but it's still a curious one.
nm dumps on my builds show ap_pcalloc as in there, but I have no idea why the linker is complaining about it not being there. Non-mod_ssl builds don't have this issue, so it has lead me to think this may have to do with the EAPI patches.
/dale