updated style

.clang-format

@@ -28,5 +28,14 @@ SpacesInParentheses: 'false'
 Standard: Cpp11
 TabWidth: '2'
 UseTab: ForIndentation
+IncludeCategories:
+  - Regex:           '^"(llvm-c|clang-c)/'
+    Priority:        2
+  - Regex:           '^"(llvm|clang)/'
+    Priority:        3
+  - Regex:           '^(<|"(gtest|isl|json)/)'
+    Priority:        4
+  - Regex:           '.*'
+    Priority:        1
 
 ...