cmake parallel jobs (#519)

* cmake parallel jobs

Author: Alexander-Makaryev

utils/command_build_cmake_clib.py

@@ -122,7 +122,13 @@ def run(self):
             "-DDPNP_BACKEND_TESTS:BOOL=" + enable_tests
         ]
 
+        # didn't find how to add it inside cmake, that is why this is here
+        import multiprocessing
+        cpu_count = multiprocessing.cpu_count()
+        # possible that jobs count must be +-1 against CPUs count
+        jobs = "-j" + str(cpu_count)
+
         self.spawn(["cmake"] + cmake_args + [backend_directory])
         if not self.dry_run:
-            self.spawn(["cmake", "--build", abs_build_temp_path])
+            self.spawn(["cmake", "--build", abs_build_temp_path, jobs])
             self.spawn(["cmake", "--install", abs_build_temp_path])