This reverts commit 8c0b2c68.

This reverts commit 6aa581d2.

This reverts commit 82b326e6.

Add section to promote the build from tar archives.

With --single-process option, nghttpx will run in a single process
mode where master and worker are unified into one process.  nghttpx
still spawns additional process for neverbleed.  In the single process
mode, signal handling is disabled.

This commit adds 2 new options to handle X-Forwarded-Proto header
field.  The --add-x-forwarded-proto option makes nghttpx append
X-Forwarded-Proto value.  The --strip-incoming-x-forwarded-proto
option makes nghttpx to strip the header field from client.

Previously, nghttpx always strips incoming header field, and set its
own header field.  This commit changes this behaviour.  Now nghttpx
does not strip, and append X-Forwarded-Proto header field by default.
The X-Forwarded-For, and Forwarded header fields are also handled in
the same way.  To recover the old behaviour, use
--add-x-forwarded-proto and --strip-incoming-x-forwarded-proto
options.

The namespace shrpx::ssl was also renamed as shrpx::tls.

nghttp2::ssl namespace was also renamed as nghttp2::tls.

Previously, we drop connection if server certificate verification
fails after handshake.  With this commit, we fail handshake if that
happens.

This reverts commit b4337d1b.

nghttpx: Retry getaddrinfo without AI_ADDRCONFIG