Fix for bug #8609: radius setting for hair child particles not symmetrical.

Bug might have actually caused more issues, there were some assumptions
that ParticleCacheKey and ParticleKey structs had members in the same order,
but the rotation was in a different place.

source/blender/blenkernel/BKE_particle.h

@@ -113,8 +113,8 @@ typedef struct ParticleSeam{
 typedef struct ParticleCacheKey{
 	float co[3];
 	float vel[3];
-	float col[3];
 	float rot[4];
+	float col[3];
 	int steps;
 } ParticleCacheKey;