seL4_libs: remove autoconf.h from seL4_libs

this commit removes autoconf.h generation from each lib and
append '#include <<lib_name>/gen_config.h>' after each
'#include <autoconf.h>' since autoconf.h is only the for the
kernel config now. This is a temporarily solution, since we
currently don't have a way to tell which header files each file
is trying to include when it includes 'autoconf.h'

trivial: style changed files

sel4test: add RPC support

This just adds a few members to sel4test structs that enable use of
sel4rpc in sel4test.

libsel4test: Add timeout and a util function for RPC Timer requests

* Document sel4test_time interface
* Remove SEL4TEST_TIME_PERIODIC_START in favor of a more generic TIMEOUT value

SELFOUR-1056: add support for periodic requests

SELFOUR-1056: add util enum to define communication codes between sel4test-test and sel4test-driver

sel4test: trivial, minor style fixes

sel4test: refactor test result status into an enum

This allows tests to specify SUCCESS, FAILURE or ABORT. ABORT indicates
a fatal failure where the tests must stop. It replaces two global
variables to simplify and reduce global state.

It also changes sel4test_start_new_test to sel4test_reset, which resets
the state of the global variables in this library used for tracking the
current test_result_t.

is_aborted is removed as its no longer neccessary.

sel4test: simplify output buffering

- remove BUFFER_OUTPUT, as PRINT_XML implies it
- use config_set where possible
- replace interface with the following:
sel4test_start_printf_buffer: start buffering output
sel4test_end_printf_buffer: dump output and stop buffering
- remove a lot of ifdefs. sel4test is not build for performance
and its
best we compile as much code as possible.
sel4test_start_printf_buffer
does nothing if PRINT_XML is not enabled.

SELFOUR-642 Fix typo (sel4test_start_new_test)

SELFOUR-642 move parts of libsel4test that depend on other libraries to
sel4test/libsel4testsupport

Rename `prototype.h` to `testutil.h` and `test.c` to `testutil.c`.