treewide: "require" + "use" cleanup and docs

There's a bunch of leftover "require" and "use" statements we no
longer need and can get rid of, along with some excessive
imports via "use".

IO::Handle usage isn't always obvious, so add comments
describing why a package loads it.  Along the same lines,
document the tmpdir support as the reason we depend on
File::Temp 0.19, even though every Perl 5.10.1+ user has it.

While we're at it, favor "use" over "require", since it it gives
us extra compile-time checking.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/GitHTTPBackend.pm b/lib/PublicInbox/GitHTTPBackend.pm
index d1132fb7..81ff23fc 100644
--- a/lib/PublicInbox/GitHTTPBackend.pm
+++ b/lib/PublicInbox/GitHTTPBackend.pm
@@ -7,7 +7,7 @@ package PublicInbox::GitHTTPBackend;
 use strict;
 use warnings;
 use Fcntl qw(:seek);
-use IO::Handle;
+use IO::Handle; # ->flush
 use HTTP::Date qw(time2str);
 use PublicInbox::Qspawn;
 use PublicInbox::Tmpfile;