Set sizes and locations of floating-point bit fields
H5T.set_fields(type_id,spos,epos,esize,mpos,msize) sets the locations and sizes of the various floating-point bit fields. spos is the sign position. epos is the exponent in bits. esize is the size of exponent in bits. mpos is the mantissa bit position. msize is the size of the mantissa in bits.