Use CMake string(TIMESTAMP) for portable compile timestamp

The previous usage of the date command is not portable across different platforms. date is not guaranteed to be available and the format varies.

Replace it with CMake's built-in string(TIMESTAMP) command which generates a string with the given timestamp format independent of the platform. This commit changes it to use "%y%m%d" format for a YYMMDD timestamp commonly used for compilation.

core/src/main/cpp/CMakeLists.txt

@@ -28,11 +28,7 @@ string (REGEX REPLACE "[\n\t\r]" "" CURRENT_BRANCH ${CURRENT_BRANCH})
 message(STATUS "git current branch = ${CURRENT_BRANCH}")
 
 # 获取生成时间
-execute_process(
-  COMMAND date +"%y%m%d"
-  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} 
-  OUTPUT_VARIABLE COMPILE_TIME
-)
+string(TIMESTAMP COMPILE_TIME "%y%m%d")
 string (REGEX REPLACE "[\n\t\r]" "" COMPILE_TIME ${COMPILE_TIME})
 string(REGEX REPLACE "\"" "" COMPILE_TIME ${COMPILE_TIME})
 
@@ -70,4 +66,4 @@ include_directories("${GO_SOURCE}")
 link_directories("${GO_OUTPUT_BASE}/${CMAKE_ANDROID_ARCH_ABI}")
 
 add_library(bridge SHARED main.c jni_helper.c bridge_helper.c)
-target_link_libraries(bridge log clash)
+target_link_libraries(bridge log clash)