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, 2 deletions

diff --git a/lib/PublicInbox/TLS.pm b/lib/PublicInbox/TLS.pm
index 0b9a55df..1bbb229a 100644
--- a/lib/PublicInbox/TLS.pm
+++ b/lib/PublicInbox/TLS.pm
@@ -5,8 +5,6 @@
 package PublicInbox::TLS;
 use strict;
 use IO::Socket::SSL;
-require Carp;
-use Errno qw(EAGAIN);
 use PublicInbox::Syscall qw(EPOLLIN EPOLLOUT);
 
 sub err () { $SSL_ERROR }