Revert "Log request allocation failures"

This reverts commit da0b2ab8cb3e2207519d8f2fd67ff4ec05cf52c3 which helps avoid a merge conflict with https://github.com/jech/polipo/commit/6bb7900e512f2391a957801723d326c3ed3450a7
and the revertion of https://github.com/berkley4/polipo/commit/150f4c79e9f7143a57ec876a8cd98f3c2c172269

It will be re-committed later on.
Revert "local.c: avoid a NULL dereference on error."

This reverts commit 150f4c7 otherwise upstream commit https://github.com/jech/polipo/commit/6bb7900e512f2391a957801723d326c3ed3450a7
would need altering to the effect that it would not make much sense.
Revert "dns.c: check return value."

This reverts commit 44fd37c which is now superceded by
upstream commit https://github.com/jech/polipo/commit/b0dc73a2547be7f29e0dead624f8720b718bc7f5
Revert "Fix a crash due to brittle va_lists on x86_64"

This reverts commit 3bec840 which is now superceded by
upstream commit https://github.com/jech/polipo/commit/d7cf597ffebde4e073b5ae005d53279681ea9258
Revert "server.c: Fixing unused variable."

This reverts commit 29f88db.

Needed because upstream commit jech@cbec2ad removes the second part of this
and causes the upstream merge to fail.

The first part will be re-committed later on.
Merge remote-tracking branch 'upstream/master' into all-changes