Use more modern CMake syntax.

src/CMakeLists.txt

@@ -1,8 +1,4 @@
-project (ndhc)
-
-cmake_minimum_required (VERSION 2.6)
-
-include_directories("${PROJECT_SOURCE_DIR}")
+project (ndhc DESCRIPTION "dhcp4 client" LANGUAGES C)
 
 set(RAGEL_IFCHD_PARSE ${CMAKE_CURRENT_BINARY_DIR}/ifchd-parse.c)
 set(RAGEL_CFG_PARSE ${CMAKE_CURRENT_BINARY_DIR}/cfg.c)
@@ -25,7 +21,26 @@ add_custom_command(
   VERBATIM
   )
 
-file(GLOB NDHC_SRCS "*.c")
-
-add_executable(ndhc ${RAGEL_CFG_PARSE} ${RAGEL_IFCHD_PARSE} ${NDHC_SRCS})
-target_link_libraries(ndhc ncmlib)
+add_executable(ndhc ${RAGEL_CFG_PARSE} ${RAGEL_IFCHD_PARSE})
+target_sources(ndhc PRIVATE
+  "arp.c"
+  "ifchd.c"
+  "netlink.c"
+  "sockd.c"
+  "dhcp.c"
+  "ifset.c"
+  "nl.c"
+  "state.c"
+  "duiaid.c"
+  "leasefile.c"
+  "options.c"
+  "sys.c"
+  "ifchange.c"
+  "ndhc.c"
+  "rfkill.c"
+)
+target_include_directories(ndhc PRIVATE
+  "${PROJECT_SOURCE_DIR}"
+  "${PROJECT_SOURCE_DIR}/../ncmlib"
+  )
+target_link_libraries(ndhc PUBLIC ncmlib)