Change win32 file suffix
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index 312fd17..b097c37 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -842,7 +842,7 @@
 include/grpc/impl/codegen/atm.h \
 include/grpc/impl/codegen/atm_gcc_atomic.h \
 include/grpc/impl/codegen/atm_gcc_sync.h \
-include/grpc/impl/codegen/atm_win32.h \
+include/grpc/impl/codegen/atm_windows.h \
 include/grpc/impl/codegen/log.h \
 include/grpc/impl/codegen/port_platform.h \
 include/grpc/impl/codegen/slice.h \
@@ -850,7 +850,7 @@
 include/grpc/impl/codegen/sync.h \
 include/grpc/impl/codegen/sync_generic.h \
 include/grpc/impl/codegen/sync_posix.h \
-include/grpc/impl/codegen/sync_win32.h \
+include/grpc/impl/codegen/sync_windows.h \
 include/grpc/impl/codegen/time.h \
 include/grpc++/impl/codegen/config.h \
 include/grpc++/impl/codegen/config_protobuf.h \