regen build file

tools/doxygen/Doxyfile.c++.internal

@@ -840,7 +840,6 @@ src/cpp/server/secure_server_credentials.h \
 src/cpp/client/create_channel_internal.h \
 src/cpp/common/create_auth_context.h \
 src/cpp/server/dynamic_thread_pool.h \
-src/cpp/server/fixed_size_thread_pool.h \
 src/cpp/server/thread_pool_interface.h \
 src/cpp/client/secure_credentials.cc \
 src/cpp/common/auth_property_iterator.cc \
@@ -864,7 +863,6 @@ src/cpp/proto/proto_utils.cc \
 src/cpp/server/async_generic_service.cc \
 src/cpp/server/create_default_thread_pool.cc \
 src/cpp/server/dynamic_thread_pool.cc \
-src/cpp/server/fixed_size_thread_pool.cc \
 src/cpp/server/insecure_server_credentials.cc \
 src/cpp/server/server.cc \
 src/cpp/server/server_builder.cc \