Re: Patch: Implement failover on libpq connect level.

Hello, Victor.

> I'm sending new version of patch.
> 
> I've replaced readonly option with target_server_type (with JDBC
> compatibility alias targetServerType), 
> 
> use logic of setting defaults based on number of hosts in the connect
> string instead of complicated condition in the state machine,
> 
> added checks for return values of memory allocation function.
> 
> Also, I've solved pg_usleep problem by linking pgsleep.c into libpq
> along with some other libpgport objects which are already linked there.
> 
> Thus client applications don't need to link with libpgport and libpq
> shared library is self-containted.

This patch doesn't apply to master branch:

```
$ git apply ~/temp/libpq-failover-8.patch
/home/eax/temp/libpq-failover-8.patch:184: trailing whitespace.
check: 
/home/eax/temp/libpq-failover-8.patch:252: trailing whitespace.
	/* 
/home/eax/temp/libpq-failover-8.patch:253: trailing whitespace.
	 *  Validate target_server_mode option 
/home/eax/temp/libpq-failover-8.patch:254: trailing whitespace.
	 */ 
/home/eax/temp/libpq-failover-8.patch:306: trailing whitespace.
			appendPQExpBuffer(&conn->errorMessage, 
error: src/interfaces/libpq/t/001-multihost.pl: already exists in
working directory

$ git diff
```

-- 
Best regards,
Aleksander Alekseev