package/coreutils: install base64 under /bin iso /usr/bin to match busybox

Fixes #11816

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 873fa4f01fa7cdd61450f46c4f51ddcec258b230)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/coreutils/coreutils.mk

@@ -55,7 +55,7 @@ COREUTILS_CONF_ENV = ac_cv_c_restrict=no \
 	MAKEINFO=true \
 	INSTALL_PROGRAM=$(INSTALL)
 
-COREUTILS_BIN_PROGS = cat chgrp chmod chown cp date dd df dir echo false \
+COREUTILS_BIN_PROGS = base64 cat chgrp chmod chown cp date dd df dir echo false \
 	kill link ln ls mkdir mknod mktemp mv nice printenv pwd rm rmdir \
 	vdir sleep stty sync touch true uname join