[all] be smarter about getting the git version

obs/CMakeLists.txt

@@ -32,17 +32,16 @@ add_compile_options(
 set(EXE_FLAGS "-Wl,--gc-sections")
 set(CMAKE_C_STANDARD 11)
 
-execute_process(
-	COMMAND			cat ../VERSION
-	WORKING_DIRECTORY	${PROJECT_SOURCE_DIR}
-	OUTPUT_VARIABLE		BUILD_VERSION
-	OUTPUT_STRIP_TRAILING_WHITESPACE
-)
-
-add_definitions(-D BUILD_VERSION='"${BUILD_VERSION}"')
 add_definitions(-D ATOMIC_LOCKING)
 get_filename_component(PROJECT_TOP "${PROJECT_SOURCE_DIR}/.." ABSOLUTE)
 
+add_custom_command(
+	OUTPUT	${CMAKE_BINARY_DIR}/version.c
+		${CMAKE_BINARY_DIR}/_version.c
+	COMMAND	${CMAKE_COMMAND} -P
+		${PROJECT_TOP}/version.cmake
+)
+
 include_directories(
 	${PROJECT_SOURCE_DIR}/include
 	${CMAKE_BINARY_DIR}/include
@@ -55,6 +54,7 @@ link_libraries(
 )
 
 set(SOURCES
+	${CMAKE_BINARY_DIR}/version.c
 	main.c
 	lg.c
 )