Resolver: fixed resend on malformed responses.

DNS request resend on malformed responses was broken in 98876ce2a7fd (1.5.8).

Reported by Pramod Korathota.
Reset of r->uri.len on URI parsing errors.

This ensures that debug logging and the $uri variable (if used in
400 Bad Request processing) will not try to access uninitialized
memory.

Found by Sergey Bobrov.
Upstream: ngx_http_upstream_store() error handling fixes.

Previously, ngx_http_map_uri_to_path() errors were not checked in
ngx_http_upstream_store().  Moreover, in case of errors temporary
files were not deleted, as u->store was set to 0, preventing cleanup
code in ngx_http_upstream_finalize_request() from removing them.  With
this patch, u->store is set to 0 only if there were no errors.

Reported by Feng Gu.
Core: fixed default log initialization.

The ngx_log_insert() function may invalidate pointer passed to it,
so make sure to don't use it after the ngx_log_insert() call.
Core: use uppercase hexadecimal digits for percent-encoding.

RFC3986 says that, for consistency, URI producers and normalizers
should use uppercase hexadecimal digits for all percent-encodings.

This is also what modern web browsers and other tools use.

Using lowercase hexadecimal digits makes it harder to interact with
those tools in case when use of the percent-encoded URI is required,
for example when $request_uri is part of the cache key.

Signed-off-by: Piotr Sikora <piotr@cloudflare.com>
GeoIP: not all variable fields were initialized.

The ngx_http_geoip_city_float_variable and
ngx_http_geoip_city_int_variable functions did not always initialize
all variable fields like "not_found", which could lead to empty values
for those corresponding nginx variables randomly.
Upstream: SSL handshake timeouts.

Timeout may not be set on an upstream connection when we call
ngx_ssl_handshake() in ngx_http_upstream_ssl_init_connection(),
so make sure to arm it if it's not set.

Based on a patch by Yichun Zhang.
SSL: misplaced space in debug message.
Bigger iovec buffer in ngx_readv_chain().

This helps to reduce likelyhood of memory allocations in ngx_readv_chain(),
which are known to lead to noticeable effects in some cases, see
http://mailman.nginx.org/pipermail/nginx/2014-July/044512.html.
SSL: fix build with OPENSSL_NO_ENGINE and/or OPENSSL_NO_OCSP.

This is really just a prerequisite for building against BoringSSL,
which doesn't provide either of those features.

Signed-off-by: Piotr Sikora <piotr@cloudflare.com>