Update the OptiX reference images. Also, fix the outdated output for test_str_ops, which has been broken since the change to string hashes.

Signed-off-by: Tim Grant <[email protected]>

Author: tgrant-nv

testsuite/testoptix-noise/ref/out.exr

@@ -16,8 +16,8 @@ temp:  abracadabra
 temp2: open sesame
 str:             default
 hash(str):       3d6b922d
-strlen(str):     7
-getchar(str, 0): 100
+strlen(str):     0
+getchar(str, 0): 0
 str: userdata string
 
 Output Cout to test_spline.exr