fix formatting for public header files

- ensure all public headers files adhere to clang-format
- preserve one-per-line for enums by adding trailing comma
- preserve include order for en/disable_warning.h

Change-Id: I78dbd0527a294ab2ec5f074fb426e48b20c393e6
diff --git a/include/ceres/internal/reenable_warnings.h b/include/ceres/internal/reenable_warnings.h
index 7e41025..2c5db06 100644
--- a/include/ceres/internal/reenable_warnings.h
+++ b/include/ceres/internal/reenable_warnings.h
@@ -32,7 +32,7 @@
 #undef CERES_WARNINGS_DISABLED
 
 #ifdef _MSC_VER
-#pragma warning( pop )
+#pragma warning(pop)
 #endif
 
 #endif  // CERES_WARNINGS_DISABLED