I then ran ldoconfig. I still had to use CFLAGS=-I/usr/local/cuda/include LDFLAGS=-L/usr/lib64/nvidia in order to have gpu mining support enabled even though /etc/ld.so.conf.d/local.conf still had these lines:
/usr/local/cuda/lib64/
/usr/local/cuda/lib/
ld.so.conf (et. al.) only affects
runtime linking, not
compile time linking. Likewise the LD_LIBRARY_PATH environment variable only has any effect on runtime linking.
To the best of my knowledge, there exists no compile-time counterpart to ld.so.conf. However, there is an environment variable similar to LD_LIBRARY_PATH. It is
LIBRARY_PATH. Anything set in this variable will be searched by gcc during the link stage. However, it would appear you still need to specify your CFLAGS, since you're asking it to include a non-standard path.