Pinpoint reason for the multithreading crash

- cut-and-pasted whole source code from RayTracingWeekend.jl
  - crash doesn't occur then
- Commented out redefinitions that make no difference on the crash
- The problems seems related to the initialization of `TRNG` and its use in related functions, and my aggressive use of @inline...
- search for `claforte CRASH` for my debugging notes

Author: claforte

src/RayTracingWeekend.jl

@@ -4,10 +4,12 @@ using Images, LinearAlgebra, Random, RandomNumbers.Xorshifts, StaticArrays
 
 export color_vec3_in_rgb, default_camera, get_ray, hit, near_zero, point, random_between, random_vec2, 
         random_vec2_in_disk, random_vec3, random_vec3_in_sphere, random_vec3_on_sphere, ray_color, ray_to_HitRecord, reflect, 
-        reflectance, refract, render, reseed!, rgb, rgb_gamma2, skycolor, squared_length, trand
+        reflectance, refract, render, reseed!, rgb, rgb_gamma2, scatter, skycolor, squared_length, trand
 export Camera, Dielectric, Hittable, HittableList, HitRecord, Lambertian, Material, Metal, Ray, Scatter, Sphere, Vec3
 export scene_2_spheres, scene_4_spheres, scene_blue_red_spheres, scene_diel_spheres, scene_random_spheres
 
+export TRNG 
+
 const Vec3{T<:AbstractFloat} = SVector{3, T}
 
 # Adapted from @Christ_Foster's: https://discourse.julialang.org/t/ray-tracing-in-a-week-end-julia-vs-simd-optimized-c/72958/40

src/old_proto.jl

@@ -4,7 +4,7 @@
 
 using BenchmarkTools, Images, InteractiveUtils, LinearAlgebra, StaticArrays
 using LoopVectorization: @turbo
-using SIMD: @simd
+#using SIMD: @simd
 
 Threads.nthreads()