* icall.c (ves_icall_System_Enum_ToObject): in case of big endian
and s2 > s1, just copy lower bytes to be compatible with little
endian (i.e. 64bit value & 0xffffffff --> 32bit value)
+ (ves_icall_System_Enum_ToObject): and likewise for s1 > s2
* unicode.c (ves_icall_iconv_new_encoder): decide on big_endian,
force big_endian to be 1 for big endian machines