log: add log_error_errno

Prints error message with strerror(errno) attached, for convenience.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/log.h

@@ -37,6 +37,8 @@ enum log_level {
 #define log_error(x, ...) LOG(ERROR, x, ##__VA_ARGS__)
 #define log_fatal(x, ...) LOG(FATAL, x, ##__VA_ARGS__)
 
+#define log_error_errno(x, ...) LOG(ERROR, x ": %s", ##__VA_ARGS__, strerror(errno))
+
 struct log;
 struct log_target;