meson: Check cairo-png dependency

Should check whether libpng dependent methods are available or not

Fixes: gstreamer/gst-build#128
35 jobs for !225 with fix-msvc-cairo in 26 seconds (queued for 7 seconds)
detached
Status Job ID Name Coverage
  Build Docker
passed #5159599
alpine amd64 manifest builder docker

00:00:12

passed #5159598
android docker

00:00:12

passed #5159596
cerbero fedora amd64 docker

00:00:16

passed #5159595
fedora amd64 docker

00:00:12

passed #5159601
gst-indent amd64 docker

00:00:16

 
  Preparation
passed #5159604
gst indent

00:00:09

manual #5159603
manual
manifest
 
  Build
created #5159621
gstreamer
build cerbero cross-android universal
created #5159629
gst-ios-13.2
build cerbero cross-ios universal
created #5159623
gstreamer
build cerbero cross win32
created #5159625
gstreamer
build cerbero cross win64
created #5159619
gstreamer
build cerbero fedora x86_64
created #5159627
gst-macos-10.15
build cerbero macos x86_64
created #5159631
1809 gstreamer-windows windows docker
build cerbero msvc x86_64
created #5159611
build clang fedora x86_64
created #5159617
1809 windows docker allowed to fail manual
build msys2
created #5159606
build nodebug fedora x86_64
created #5159608
build static fedora x86_64
created #5159609
build static nodebug fedora x86_64
created #5159612
1809 windows docker
build vs2017 amd64
created #5159614
1809 windows docker
build vs2017 x86
 
  Test
created #5159634
gstreamer
check fedora
created #5159637
gstreamer
integration testsuites fedora 1/4
created #5159638
gstreamer
integration testsuites fedora 2/4
created #5159639
gstreamer
integration testsuites fedora 3/4
created #5159640
gstreamer
integration testsuites fedora 4/4
created #5159645
gstreamer
valgrind bad
created #5159642
gstreamer
valgrind base
created #5159641
gstreamer
valgrind core
created #5159646
gstreamer
valgrind ges
created #5159643
gstreamer
valgrind good
created #5159644
gstreamer
valgrind ugly
 
  Integrate
created #5159647
cross-android universal examples
created #5159649
gst-ios-13.2
cross-ios universal examples
created #5159648
documentation