[Support] Simplify the continuation condition in encodeSLEB128 (NFC) (#165651)
The boolean expression to determine if more bytes are needed for a
signed LEB128 value is quite complex:
!((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
((Value == -1) && ((Byte & 0x40) != 0))))
This patch simplifies it to an equivalent expression using a ternary
operator, which is much easier to understand.