glib: Add accessor functions for PopplerAttachment

Issue #715
6 jobs for GDateTime in 5 minutes and 9 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #1626858
build

00:04:04

passed #1626863
build_android

00:01:51

passed #1626859
build_clang_libcpp

00:04:50

passed #1626862
build_clazy

00:02:38

passed #1626861
build_mingw64_fedora

00:03:04

passed #1626860
build_ubuntu_16_04

00:05:08