configure: error: C preprocessor "/lib/cpp" fails sanity check
I've gotten this error several times while trying to install packages. I don't know why it happens as I do have gcc installed. I tried removing it, reinstalling, and updating, but it doesn't change. I use Slackware 14.1 64-bit. /lib/cpp is a link to /usr/bin/cpp.
Any ideas how to fix this?