FIR translates:
```
when (x) {
1, 2, 3 -> action
else -> other_action
}
```
to an IR structure with nested ors:
```
if ((x == 1 || x == 2) || (x == 3)) action
else other_action
```
This change allows that to turn into switch instructions in the
JVM backend.
Effectively, the following when structure:
when (s) {
s1, s2 -> e1,
s3 -> e2,
s4 -> e3,
...
else -> e
}
is implemented as:
when (s.hashCode()) {
h1 -> {
if (s == s1)
e1
else if (s == s2)
e1
else if (s == s3)
e2
else
e
}
h2 -> if (s == s3) e2 else e,
...
else -> e
}
where s1.hashCode() == s2.hashCode() == s3.hashCode() == h1,
s4.hashCode() == h2.
A tableswitch or lookupswitch is used for the hash code lookup.
Change-Id: I087bf623dbb4a41d3cc64399a1b42342a50757a6