style: 改进 SGV 相关声明

src/sgr.h

@@ -37,11 +37,3 @@
 #define C_BRIGHT_MAGENTA "\033[95m"
 #define C_BRIGHT_CYAN    "\033[96m"
 #define C_BRIGHT_WHITE   "\033[97m"
-
-#define C_OFF   "\033[0m" // 复原
-#define C_BOLD  "\033[1m" // 粗体
-#define C_DIM   "\033[2m" // 半亮度
-#define C_ITALIC "\033[3m" // 斜体
-#define C_CYAN  "\033[36m" // 
-#define C_GREEN "\033[32m"
-#define C_RED   "\033[31m"