refactor(infra/packet_parser): from *.cpp to *.c

infra/packet_parser/CMakeLists.txt

@@ -1,10 +1,10 @@
 add_library(packet
-    packet_utils.cpp
-    packet_parser.cpp
-    packet_builder.cpp
-    packet_filter.cpp
-    packet_dump.cpp
-    checksum.cpp)
+    packet_utils.c
+    packet_parser.c
+    packet_builder.c
+    packet_filter.c
+    packet_dump.c
+    checksum.c)
 target_include_directories(packet PUBLIC ${CMAKE_CURRENT_LIST_DIR})
 target_include_directories(packet PUBLIC ${CMAKE_SOURCE_DIR}/deps/uthash)
 target_include_directories(packet PUBLIC ${CMAKE_SOURCE_DIR}/include)