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, 0 insertions, 1 deletions

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 6eea2b9c..1c74a596 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -15,7 +15,6 @@ use strict;
 use warnings;
 use base qw(Exporter);
 use Symbol qw(gensym);
-use IO::Handle;
 use PublicInbox::ProcessPipe;
 our @EXPORT_OK = qw/which spawn popen_rd/;
 sub RLIMITS () { qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA) }