build: fix unused/uninitialized variable warnings

Fix a few warnings about unused and uninitialized variables.

Also fix util/subst.c to include <sys/time.h> to avoid using
undeclared functions gettimeofday() and futimes().

Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
6 files changed