Leap seconds are incorrectly counted when leapsecond file is not present/found

[drsteve]

Running make check without installing first means that there's no data directory.
This then means that the leap seconds file isn't found and running check_libLanlGeoMag yields the following error:

Running suite(s): LGM Master Suite
 LEAP_SECOND_TESTS
Lgm_LoadLeapSeconds: Could not open Lgm_LeapSecondDates.dat file!
                     Setting the leap second values that I know about
                     (latest leap second I know about was introduced on
                     20170101 (total leap seconds is 37))
Lgm_LoadLeapSeconds: Could not open Lgm_LeapSecondDates.dat file!
                     Setting the leap second values that I know about
                     (latest leap second I know about was introduced on
                     20170101 (total leap seconds is 37))
Testing to see if 19920630 is a leap second date (it should be)
Lgm_LoadLeapSeconds: Could not open Lgm_LeapSecondDates.dat file!
                     Setting the leap second values that I know about
                     (latest leap second I know about was introduced on
                     20170101 (total leap seconds is 37))
Lgm_LoadLeapSeconds: Could not open Lgm_LeapSecondDates.dat file!
                     Setting the leap second values that I know about
                     (latest leap second I know about was introduced on
                     20170101 (total leap seconds is 37))
Testing to see if 19920629 is a leap second date (it should not be)
Lgm_LoadLeapSeconds: Could not open Lgm_LeapSecondDates.dat file!
                     Setting the leap second values that I know about
                     (latest leap second I know about was introduced on
                     20170101 (total leap seconds is 37))
Lgm_LoadLeapSeconds: Could not open Lgm_LeapSecondDates.dat file!
                     Setting the leap second values that I know about
                     (latest leap second I know about was introduced on
                     20170101 (total leap seconds is 37))
Check to see that number of leap seconds by 2009/6/1 is 34
 VECTOR_OPERATION_TESTS
Check that Lgm_Magnitude gives known answer: Passed.
Check that Lgm_NormalizeVector result has magnitude of 1: Passed.
60%: Checks: 5, Failures: 2, Errors: 0
check_libLanlGeoMag.c:29:F:Leap seconds:test_IsLeapSecondDay_01:0: 1992/6/30 should be a leap second day, with sec_in_day = 86401 (got 86400)
check_libLanlGeoMag.c:53:F:Leap seconds:test_GetLeapSeconds:0: Should be 34 leap seconds by 2009/6/1, not 45.315810

Note that these tests pass when the leap second file is present