FcConfigParseAndLoad*() should returns false on config errors

Fixes fontconfig/fontconfig#168

Reported by Lawrence D'Oliveiro
3 jobs for issue/168 in 5 minutes and 37 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #436194
mingw-build

00:04:42

passed #436192
shared-build

00:05:37

passed #436193
static-build

00:04:29