compel cli: show includes

1. Add "compel includes" command, to be used for parasite *loading*
   code compilation.

2. Add includes to output of "compel cflags", which is used for parasite
   code compilation.

Now, this patch looks big and complex, this is mostly because we want
compel cli to work for both uninstalled (right from the source tree)
and installed cases. The paths to be printed are quite different for
these two cases, so I had to introduce a wrapper for a non-installed
case. The wrapper sets an environment variable, which compel binary
uses as a path to non-installed file. If this env var is not set,
it means compel is installed so no tricks are needed.

Note the wrapper is only provided for the compel-host binary, as compel
(which differs from compel-host in case of cross-compiling) is not
executed from within the source tree.

Because of the wrapper, the original binary had to be renamed, thus the
changes to Makefiles and .gitignore.

travis-ci: success for More polishing for compel cli
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

.gitignore

@@ -17,7 +17,7 @@ tags
 TAGS
 Makefile.local
 compel/compel
-compel/compel-host
+compel/compel-host-bin
 images/*.c
 images/*.h
 images/google/protobuf/*.c