added constant for seconds between posix epoch (1970) and rtems epoch (1988).

Formerly this constant was in the file src/time.c.

c/src/exec/posix/headers/time.h

@@ -7,6 +7,17 @@
 #ifndef __RTEMS_POSIX_TIME_h
 #define __RTEMS_POSIX_TIME_h
 
+#include <rtems/score/tod.h>
+
+/*
+ *  Seconds from January 1, 1970 to January 1, 1988.  Used to account for
+ *  differences between POSIX API and RTEMS core.
+ */
+ 
+#define POSIX_TIME_SECONDS_1970_THROUGH_1988 \
+  (((1987 - 1970 + 1)  * TOD_SECONDS_PER_NON_LEAP_YEAR) + \
+  (4 * TOD_SECONDS_PER_DAY))
+
 Watchdog_Interval _POSIX_Time_Spec_to_interval(
   const struct timespec *time
 );

c/src/exec/posix/include/rtems/posix/time.h

@@ -7,6 +7,17 @@
 #ifndef __RTEMS_POSIX_TIME_h
 #define __RTEMS_POSIX_TIME_h
 
+#include <rtems/score/tod.h>
+
+/*
+ *  Seconds from January 1, 1970 to January 1, 1988.  Used to account for
+ *  differences between POSIX API and RTEMS core.
+ */
+ 
+#define POSIX_TIME_SECONDS_1970_THROUGH_1988 \
+  (((1987 - 1970 + 1)  * TOD_SECONDS_PER_NON_LEAP_YEAR) + \
+  (4 * TOD_SECONDS_PER_DAY))
+
 Watchdog_Interval _POSIX_Time_Spec_to_interval(
   const struct timespec *time
 );

cpukit/posix/include/rtems/posix/time.h

@@ -7,6 +7,17 @@
 #ifndef __RTEMS_POSIX_TIME_h
 #define __RTEMS_POSIX_TIME_h
 
+#include <rtems/score/tod.h>
+
+/*
+ *  Seconds from January 1, 1970 to January 1, 1988.  Used to account for
+ *  differences between POSIX API and RTEMS core.
+ */
+ 
+#define POSIX_TIME_SECONDS_1970_THROUGH_1988 \
+  (((1987 - 1970 + 1)  * TOD_SECONDS_PER_NON_LEAP_YEAR) + \
+  (4 * TOD_SECONDS_PER_DAY))
+
 Watchdog_Interval _POSIX_Time_Spec_to_interval(
   const struct timespec *time
 );