Bug: pattern length will visit illegal address in hs_compile_lit_multi

in function addLitExpression:
// Ensure that our pattern isn't too long (in characters).
if (strlen(expression) > cc.grey.limitPatternLength) {
throw CompileError("Pattern length exceeds limit.");
}
the literal pattern maybe not ended with '\0', so strlen(expression) will visit the illegal address.
maybe "strlen(expression) " should change to expLength which is user defined.

please check this bug