pixman: update internal copy to pixman-0.32.6

commit a93a3af9 introduces use of PIXMAN_TYPE_RGBA, but it's only available
in pixman >= 0.21.8. Although commit f27b2e1d bumped pixman to pixman-0.28.2,
but the change was reverted later by 7b1b5d19.

This patch updates internal copy of pixman to pixman-0.32.6 to fix the
problem.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
configure: check for pixman-1 version

commit a93a3af9 introduces use of PIXMAN_TYPE_RGBA, but it's only available
in pixman >= 0.21.8. If pixman doesn't meet the version requirement, qemu
will fail to build with following message:

qemu/ui/qemu-pixman.c: In function ‘qemu_pixelformat_from_pixman’:
qemu/ui/qemu-pixman.c:42: error: ‘PIXMAN_TYPE_RGBA’ undeclared (first use in this function)
qemu/ui/qemu-pixman.c:42: error: (Each undeclared identifier is reported only once
qemu/ui/qemu-pixman.c:42: error: for each function it appears in.)

This patch fixes the problem by checking the pixman version.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Merge remote-tracking branch 'remotes/kraxel/tags/pull-console-20140915-1' into staging

Fix pixman build failure.

# gpg: Signature made Mon 15 Sep 2014 07:15:11 BST using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"

* remotes/kraxel/tags/pull-console-20140915-1:
  configure: check for pixman-1 version
  pixman: update internal copy to pixman-0.32.6

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>