run two make tests

The first one will be without node statistics, the other with
(so there will be different code paths in scheduler's pick_server() ).
use server speed adjusted for the job also in debug messages
test also plain C file
test with a syntax error
verify during tests that also stderr is the same
disable ccache for tests, just in case
test that usage of -frewrite-includes doesn't alter warnings/errors

Clang-3.4 has bugs in -frewrite-includes that break line numbers
in messages, there's no line marker at the beginning of the resulting
file, so the file would be <stdin>, and line numbers for
"In file included from <file>:<line>:" would be off too.
fix comment
make it possible to explicitly override support for -fdiagnostics-color

Similarly the way it's possible to override -frewrite-includes.
However, there's no way to automatically detect in configure whether
the compiler turns on colors automatically (patched gcc-4.8 in Fedora)
or not (upstream gcc-4.9), because the test would need terminal
as the output, so the default in configure is off.
adjust message about ICECC_CLANG_REMOTE_CPP
workaround for gcc -fdiagnostics-show-caret failing remotely

It needs the actual file, which of course fails. So build locally
as a (optional) workaround.
initialize variable

Daemon::reannounce_environments() doesn't bother initializing
max_kids, because it's important only for first login, so there
would be a valgrind error when doing send() about uninitialized data.
use getnameinfo() instead of inet_ntoa()

We definitely can accept() at least AF_UNIX sockets, and there
the cast to sockaddr_in would be wrong, getnameinfo() is protocol-independent.
check for effective capability rather than permitted

As far as I understand it the effective ones are the ones that
are actually checked and used by the kernel.
make it possible to run tests in Valgrind
alter test starting messages a bit