Fix gcc compiler error

[RussTreadon-NOAA]

The gcc compiler requires a field width specification when formatting numeric output. Automated gcc testing flagged the line

     write(6,'(a,i,a)')  'Command line input for ',iargc(),' arguments'

in src/EnKF/gfs/src/getsigensmeanp_smooth.fd/getsigensmeanp_smooth_ncep.f90

This PR adds a field width to the integer format so that the above line reads

     write(6,'(a,i3,a)')  'Command line input for ',iargc(),' arguments'

With this change in place automated gcc testing passes.

[RussTreadon-NOAA]

@CoryMartin-NOAA and @DavidNew-NOAA , automated gcc testing flagged the formatting error described above. This PR adds a field width to the i format. This allows the gcc test to pass. I'll merge into develop once it is reviewed and approved.

[RussTreadon-NOAA]

Thank you @CoryMartin-NOAA