Replace hard coded reference to /etc with @SYSCONFDIR@

I found a reference to "/etc" in the procfs script. This changes that
reference to @SYSCONFDIR@.

init.d/procfs.in

@@ -48,7 +48,7 @@ start()
 				ebegin "Loading custom binary format handlers"
 				fmts=$(grep -hsv -e '^[#;]' -e '^[[:space:]]*$' \
 					/run/binfmt.d/*.conf \
-					"/etc"/binfmt.d/*.conf \
+					@SYSCONFDIR@/binfmt.d/*.conf \
 					""/usr/lib/binfmt.d/*.conf)
 				if [ -n "${fmts}" ]; then
 					echo "${fmts}" > /proc/sys/fs/binfmt_misc/register