Update to Firebird 3.0

[Bunth Tamás]

> Try this: firebird should dlopen("libEngine12.so") without any path. I
> think it will work. If not, passing the right --prefix to firebird's
> ./configure or something like that. Or patching the code to hardcode
> it :)

Firebird seems to use the libEngine12.so during the build to open
"metadata.fdb", and I got an error during "make firebird":
Unable to complete network request to host "localhost".
make[5]: *** [metadata.fdb] Error 1

It's because I've changed the Engine12's path to "libeEngine12.so",
and now It cannot find the file in the original file system
(firebird/gen/Release/firebird).
So now I'm looking for a way to skip this part of the build somehow,
if it is possible.
Or we should put the libEngine12.so/dll file next to the libfbclient
file. That can be done in builds/posix/make.defaults I think.