fortran, libgfortran: Assorted -mabi=ieeelongdouble I/O fixes

Another patch, this fixes:
FAIL: gfortran.dg/intrinsic_spread_2.f90   -O0  execution test
FAIL: gfortran.dg/intrinsic_spread_2.f90   -O1  execution test
FAIL: gfortran.dg/intrinsic_spread_2.f90   -O2  execution test
FAIL: gfortran.dg/intrinsic_spread_2.f90   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
FAIL: gfortran.dg/intrinsic_spread_2.f90   -O3 -g  execution test
FAIL: gfortran.dg/intrinsic_spread_2.f90   -Os  execution test
FAIL: gfortran.dg/intrinsic_unpack_2.f90   -O0  execution test
FAIL: gfortran.dg/intrinsic_unpack_2.f90   -O1  execution test
FAIL: gfortran.dg/intrinsic_unpack_2.f90   -O2  execution test
FAIL: gfortran.dg/intrinsic_unpack_2.f90   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
FAIL: gfortran.dg/intrinsic_unpack_2.f90   -O3 -g  execution test
FAIL: gfortran.dg/intrinsic_unpack_2.f90   -Os  execution test
FAIL: gfortran....