Revert new experimental libev backend due to time constraints

Due to time constraints I had to revert the new libev backend to the
service, I/O and signals monitor.  Employed instead is the tried and
tested signals based service monitor, with a small extension for an
additional I/O monitor using poll() for the I/O plugins to use.

Tried restoring the startx finit.conf directive on top of the service
implementation. However, it's currently not usable to run /usr/bin/startx
for any other user than root. I recommend using the examples/finit.conf
and run /usr/sbin/gdm instead.

finit.c:
        New run_loop() function, replaces libev ev_run().

helpers.c:
        Refactor start_process() into svc_start().

plugin.c:
        Add fds[] array for use in the io_monitor() called by the
        new run_loop().

signal.c:
        Ignore SIGCHLD. Handled by waitpid() in svc_monitor() now,
        which is called by the new run_loop().

svc.c:
        svc_register(): Optional @username parsing for the command line.
        svc_monitor(): Replaced libev callback with waitpid()
        svc_start(): Refactored to use most of helpers.c:start_process()

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile

@@ -42,7 +42,7 @@ CPPFLAGS   += -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_GNU_SOURCE
 CPPFLAGS   += -DVERSION=\"$(VERSION)\" -DWHOAMI=\"`whoami`@`hostname`\"
 CPPFLAGS   += -DPLUGIN_PATH=\"$(PLUGIN_DIR)\"
 LDFLAGS    += -rdynamic
-LDLIBS     += -ldl -lev
+LDLIBS     += -ldl
 
 prefix     ?= /usr/local
 sysconfdir ?= /etc