Successful build of v1.7.0.0 on Arch Linux

[gonsolo]

This is a patch to build v1.7.0.0 on Arch Linux:

arch.patch.gz

62 files changed, 116 insertions(+), 88 deletions(-)

I am using cmake -DMOONRAY_USE_OPTIX=NO since I'm running on Nouveau and NVK.

[gonsolo]

Maybe the cstdint related stuff can be merged to reduce the size of the patch over time, @randypacker?

grep -n "+#include" arch.patch |grep cstdint
670:+#include <cstdint>
855:+#include <cstdint>
867:+#include <cstdint>
879:+#include <cstdint>
973:+#include <cstdint>
985:+#include <cstdint>
997:+#include <cstdint>

The rest of the patch deals with:

1. Messing up PATH in CMakeLists.txt (line 10) (Issue)
2. Finding some packages (line 23)
3. Adapting to Arch's monolithic USD build (line 41 and others)
4. Commenting a fix for icc (line 60...)
5. Newer version of USD (line 183)
6. Finding python (line 382...)
7. tbb scheduler (line 435)
8. __TBB_Yield() (line 457)
9. tbb::this_task_arena (line 483)
10. std::scoped_lock instead of tbb::recursive_mutex::scoped_lock
11. Include Imath (line 658)
12. std::atomic instead of tbb::atomic (line 744...)
13. include (line 801)
14. "emit" clash (line 892)