Never, ever, ever use IGNORE_CC_MISMATCH. Recompile your kernel with the system compiler instead, and boot into it, so that /proc/version's gcc version matches what cc -v says.
Your log file is loading about 15 different XFree86 drivers (none of them, incidentally, are the nvidia one). None of them can find any hardware, or something, so you get the "no screens found" error. If this is actually the right config file that you posted, it's only referencing one nvidia driver (nvidia_drv.o), but that driver isn't ever getting loaded.
When you configured X before compiling it, you did select support for dynamic loading of modules, correct? (you need to edit the config/cf/host.def file after you copy config/cf/xf86site.def over it, BTW).
Are you sure this config file (the one you posted) is /etc/X11/XF86Config?
Are you sure this log is from the most recent attempt at running X?