decode_rs_char() should return int #13

According to documention of libfec:

The decode_ functions correct the errors in a Reed-Solomon codeword of N symbols up to the capability of the code. An optional list of "erased" symbol indices may be given in the eras_pos array to assist the decoder; this parameter may be NULL if no erasures are given. The number of erased symbols must be given in the no_eras parameter.

The decoder corrects the symbols "in place", returning the number of symbols in error. If the codeword is uncorrectable, -1 is returned and the data block is unchanged. If eras_pos is non-null, it is used to return a list of corrected symbol positions, in no particular order. This means that the array passed through this parameter must have at least nroots elements to prevent a possible buffer overflow.

The decode_ functions return a count of corrected
symbols, or -1 if the block was uncorrectible.

However, in the compatibility layer, decode_rs_char() returns void, and there is no return value in erasure_locations.