#2534 - Add JsonCpp 1.9.4 (#2535)
#2534 - Add JsonCpp 1.9.4 (#2535)

* Add JsonCpp 1.9.4

cf https://github.com/compiler-explorer/compiler-explorer/issues/2534
Companion PR on infra: https://github.com/compiler-explorer/infra/pull/481

* tiny fix to path

Co-authored-by: Patrick Quist <dda891045ad113066162ac923a134da212eb3ba7@gmail.com>
mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/compiler-explorer,dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/gcc-explorer,dkm/gcc-explorer