remove __restrict__ in cpp

Summary: Remove use of nonstandard C++. Noticed on windows in issue facebookresearch#843. (We use `__restrict__` in CUDA, where it is fine, even on windows)

Reviewed By: nikhilaravi

Differential Revision: D31006516

fbshipit-source-id: 929ba9b3216cb70fad3ffa3274c910618d83973f

Author: bottler

pytorch3d/csrc/sample_pdf/sample_pdf_cpu.cpp

@@ -32,8 +32,7 @@ void SamplePdfCpu_worker(
 
   auto bins_a = bins.accessor<float, 2>();
   auto weights_a = weights.accessor<float, 2>();
-  float* __restrict__ output_p =
-      outputs.data_ptr<float>() + start_batch * n_samples;
+  float* output_p = outputs.data_ptr<float>() + start_batch * n_samples;
 
 #ifdef USE_BINARY_SEARCH
   std::vector<float> partial_sums(n_bins);