gdk-pixbuf: fix parallel install issue

gdk-pixbuf: fix parallel install issue

This patch fixes parallel install issue that lib libpixbufloader-png.la
depends on libgdk_pixbuf-2.0.la which will be regenerated during insta-
llation, if libgdk_pixbuf-2.0.la is regenerating and at the same time
libpixbufloader-png.la links it, the error will happen.

Error message is:
* usr/bin/ld: cannot find -lgdk_pixbuf-2.0
* collect2: ld returned 1 exit status

Make an explicit dependency to the libs install targets would fix this
issue.

[YOCTO #2883]

(From OE-Core rev: e6fb5a25a098bd639be4b176f58e552404232c93)

Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>