Add POSIX prototypes for time functions, to allow external code to build

more easily within gPXE.

Note that we don't have function bodies for these functions yet.

src/include/sys/time.h

+#ifndef _SYS_TIME_H
+#define _SYS_TIME_H
+
+#include <time.h>
+
+typedef unsigned long suseconds_t;
+
+struct timeval {
+	time_t tv_sec;		/* seconds */
+	suseconds_t tv_usec;	/* microseconds */
+};
+
+struct timezone {
+	int tz_minuteswest;	/* minutes W of Greenwich */
+	int tz_dsttime;		/* type of dst correction */
+};
+
+extern int gettimeofday ( struct timeval *tv, struct timezone *tz );
+
+#endif /* _SYS_TIME_H */

src/include/time.h

+#ifndef _TIME_H
+#define _TIME_H
+
+typedef unsigned long time_t;
+
+struct tm {
+	int tm_sec;	/* seconds */
+	int tm_min;	/* minutes */
+	int tm_hour;	/* hours */
+	int tm_mday;	/* day of the month */
+	int tm_mon;	/* month */
+	int tm_year;	/* year */
+	int tm_wday;	/* day of the week */
+	int tm_yday;	/* day in the year */
+	int tm_isdst;	/* daylight saving time */
+};
+
+extern time_t time ( time_t *t );
+
+extern time_t mktime ( struct tm *tm );
+
+#endif /* _TIME_H */