Add a patch for OSX with SDK<10.12 (pytorch#15615)

Summary:
Fixes pytorch#15614

Build passing on SDK 10.9
https://dev.azure.com/ramonaoptics/feedstock-builds/_build/results?buildId=13
Pull Request resolved: pytorch#15615

Differential Revision: D13561737

Pulled By: soumith

fbshipit-source-id: 2ab0f78338d4949fa3f2735915fd96dce4bcd621

torch/csrc/autograd/profiler.h

@@ -35,11 +35,21 @@ constexpr inline size_t ceilToMultiple(size_t a, size_t b) {
   return ((a + b - 1) / b) * b;
 }
 
+#if defined(__MACH__) && !defined(CLOCK_REALTIME)
+#include <sys/time.h>
+// clock_gettime is not implemented on older versions of OS X (< 10.12).
+// If implemented, CLOCK_REALTIME will have already been defined.
+#endif
+
 inline int64_t getTime() {
 #ifdef _WIN32
   using namespace std::chrono;
   using clock = std::conditional<high_resolution_clock::is_steady, high_resolution_clock, steady_clock>::type;
   return duration_cast<nanoseconds>(clock::now().time_since_epoch()).count();
+#elif defined(__MACH__) && !defined(CLOCK_REALTIME)
+  struct timeval now;
+  gettimeofday(&now, NULL);
+  return static_cast<int64_t>(now.tv_sec) * 1000000000 + static_cast<int64_t>(now.tv_usec) * 1000;
 #else
   // clock_gettime is *much* faster than std::chrono implementation on Linux
   struct timespec t{};