Silence warnings when engine is skipped.

Silence warnings when engine is skipped.

Also, fix some mistakes.

BUG=none
TEST=manually with Fedora's default.xml

[Daiki Ueno, 2012-03-05 06:58:41]

On Fedora, we disable several engines by default (i.e. rank < 0).  In that
setting, I got a report saying that "skipped XX since its rank is lower than 0"
warning is too verbose.

Also fixes g_variant_unref() mistakes.

[Peng, 2012-03-05 15:49:42]

lgtm

http://codereview.appspot.com/5730054/diff/1/src/main.c
File src/main.c (right):

http://codereview.appspot.com/5730054/diff/1/src/main.c#newcode119
src/main.c:119: exit (1);
Maybe you would like to use EXIT_FAILURE here

http://codereview.appspot.com/5730054/diff/1/src/main.c#newcode124
src/main.c:124: exit (0);
And EXIT_SUCCESS

[Daiki Ueno, 2012-03-06 01:01:31]

JFTR, uploading a new CL to be committed, that also fixes more minor mistakes:

- remove HAVE_IBUS_ENGINE_GET_SURROUNDING_TEXT macros
- use libtool to link libm17ncommon.a
- mark some internal functions as static

https://codereview.appspot.com/5730054/diff/1/src/main.c
File src/main.c (right):

https://codereview.appspot.com/5730054/diff/1/src/main.c#newcode119
src/main.c:119: exit (1);
On 2012/03/05 15:49:42, Peng wrote:
> Maybe you would like to use EXIT_FAILURE here

Done.

https://codereview.appspot.com/5730054/diff/1/src/main.c#newcode124
src/main.c:124: exit (0);
On 2012/03/05 15:49:42, Peng wrote:
> And EXIT_SUCCESS

Done.