all: Remove support for obsolete systems

poppler/poppler#709
6 jobs from mr/issue-709 in 7 minutes and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #75143
build

00:04:16

passed #75148
build_android

00:01:05

passed #75144
build_clang_libcpp

00:04:04

passed #75147
build_clazy

00:06:33

passed #75145
build_gcc_49

00:07:41

passed #75146
build_mingw64_fedora

00:05:00