Adding version support for libtraceevent.so object.

Using the existing EVENT_PARSE_VERSION variable to construct
the .so object version string, which now consists of:

  $(EP_VERSION).$(EP_PATCHLEVEL).$(EP_EXTRAVERSION)

Looks like it was created for this purpose anyway.

The build will now produce following traeceevent libraries:

  $ ll libtraceevent*
  libtraceevent.a
  libtraceevent.so -> libtraceevent.so.1.1.0
  libtraceevent.so.1 -> libtraceevent.so.1.1.0
  libtraceevent.so.1.1.0

Also the install target will carry them:

  $ make DESTDIR=/tmp/krava prefix=/usr install
  INSTALL  trace_plugins
  INSTALL  libtraceevent.a
  INSTALL  libtraceevent.so.1.1.0

  $ find /tmp/krava/ | xargs ls -l
  ...
  /tmp/krava/usr/lib64:
  total 572
  libtraceevent.a
  libtraceevent.so -> libtraceevent.so.1.1.0
  libtraceevent.so.1 -> libtraceevent.so.1.1.0
  libtraceevent.so.1.1.0
  ...
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-v64z62fh0dwt0ueie5usrnac@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>