Revert "[BACKEND] Various bug fixes; making reductions faster (#533)".

This is a more stable commit that produce bitwise identical code to earlier
versions. Using commits after this one may lead to slightly different numerics

python/setup.py

@@ -79,7 +79,7 @@ class CMakeBuild(build_ext):
 
     def build_extension(self, ext):
         llvm_include_dir, llvm_library_dir = get_llvm()
-        self.debug = True
+        # self.debug = True
         extdir = os.path.abspath(os.path.dirname(self.get_ext_fullpath(ext.path)))
         # create build directories
         build_suffix = 'debug' if self.debug else 'release'