Cycles: Fix a few type casting warnings

Stumbled over the `integrate_surface_volume_only_bounce` kernel
function not returning the right type. The others too showed up as
warnings when building Cycles as a standalone which didn't have
those warnings disabled.

Differential Revision: https://developer.blender.org/D14558

intern/cycles/kernel/integrator/shade_surface.h

@@ -346,7 +346,7 @@ ccl_device_forceinline int integrate_surface_bsdf_bssrdf_bounce(
 }
 
 #ifdef __VOLUME__
-ccl_device_forceinline bool integrate_surface_volume_only_bounce(IntegratorState state,
+ccl_device_forceinline int integrate_surface_volume_only_bounce(IntegratorState state,
                                                                 ccl_private ShaderData *sd)
 {
   if (!path_state_volume_next(state)) {

intern/cycles/scene/geometry.cpp

@@ -180,7 +180,7 @@ bool Geometry::has_true_displacement() const
 }
 
 void Geometry::compute_bvh(
-    Device *device, DeviceScene *dscene, SceneParams *params, Progress *progress, int n, int total)
+    Device *device, DeviceScene *dscene, SceneParams *params, Progress *progress, size_t n, size_t total)
 {
   if (progress->get_cancel())
     return;

intern/cycles/scene/geometry.h

@@ -110,8 +110,8 @@ class Geometry : public Node {
                    DeviceScene *dscene,
                    SceneParams *params,
                    Progress *progress,
-                   int n,
-                   int total);
+                   size_t n,
+                   size_t total);
 
   virtual PrimitiveType primitive_type() const = 0;
 

intern/cycles/session/merge.cpp

@@ -531,7 +531,7 @@ static void read_layer_samples(vector<MergeImage> &images,
         current_layer_samples.total = 0;
         current_layer_samples.per_pixel.resize(in_spec.width * in_spec.height);
         std::fill(
-            current_layer_samples.per_pixel.begin(), current_layer_samples.per_pixel.end(), 0);
+            current_layer_samples.per_pixel.begin(), current_layer_samples.per_pixel.end(), 0.0f);
       }
 
       if (layer.has_sample_pass) {