Merge branch 'expat-pkg-config' into 'master'

Detect expat using pkg-config

See merge request !37
2 jobs for master in 126 minutes and 52 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #4884
amd64
job_clang_amd64

02:06:52

passed #4883
amd64
job_gcc_amd64

01:22:02