rusticl/program: protect against 0 length in slice::from_raw_parts

Fixes: e028baa177 ("rusticl/program: implement clCreateProgramWithBinary")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30410>

src/gallium/frontends/rusticl/api/program.rs

@@ -183,14 +183,16 @@ fn create_program_with_binary(
 ) -> CLResult<cl_program> {
     let c = Context::arc_from_raw(context)?;
     let devs = Device::refs_from_arr(device_list, num_devices)?;
-    let mut binary_status =
-        unsafe { cl_slice::from_raw_parts_mut(binary_status, num_devices as usize) }.ok();
 
     // CL_INVALID_VALUE if device_list is NULL or num_devices is zero.
     if devs.is_empty() {
         return Err(CL_INVALID_VALUE);
     }
 
+    // needs to happen after `devs.is_empty` check to protect against num_devices being 0
+    let mut binary_status =
+        unsafe { cl_slice::from_raw_parts_mut(binary_status, num_devices as usize) }.ok();
+
     // CL_INVALID_VALUE if lengths or binaries is NULL
     if lengths.is_null() || binaries.is_null() {
         return Err(CL_INVALID_VALUE);