rename instruction_set to something less ambiguous

It is a set of instruction sets, and "instruction_set" is not great for that

faiss/python/loader.py

@@ -9,9 +9,9 @@
 import logging
 
 
-def instruction_set():
+def supported_instruction_sets():
     """
-    Returns the set of supported instruction sets, see
+    Returns the set of supported CPU features, see
     https://github.com/numpy/numpy/blob/master/numpy/core/src/common/npy_cpu_features.h
     for the list of features that this set may contain per architecture.
 
@@ -46,7 +46,7 @@ def instruction_set():
 logger = logging.getLogger(__name__)
 
 try:
-    has_AVX2 = "AVX2" in instruction_set()
+    has_AVX2 = "AVX2" in supported_instruction_sets()
     if has_AVX2:
         logger.info("Loading faiss with AVX2 support.")
         from .swigfaiss_avx2 import *