contrib: fix BUILDDIR in gen-bitcoin-conf script
On master the gen-bitcoin-conf script doesn't work as it cannot find bitcoind. This is because of the build dir that is now being used since cmake.
This PR fixes it.
master
./gen-bitcoin-conf.sh
/home/marnix/projects/bitcoin/src/bitcoind not found or not executable.
PR
./gen-bitcoin-conf.sh
Generating example bitcoin.conf file in share/examples/