[testsuite gfortran] partial fix for secnds*.f

[Dominique Dhumieres]

The problem is deeper than just a rouinding problem:

#include <math.h>
#include <stdio.h>

int main()
{

    double time1;
    float time2;
    time1 = 3600.0*23.0f+60.0*59.0f+59.0f+0.001*999.0f;
    printf("%g \n", time2);
}

#include <math.h>
#include <stdio.h>

int main()
{

    float time1;
    float time2;
    time1 = 3600.0f*23.0f+60.0f*59.0f+59.0f+0.001f*999.0f;
    time2 = time1;
    printf("%g \n", time2);
}

print *, 3600.0*23.0+60.0*59.0+59.0+0.001*999.0
end

all return 86400*

Dominique