Optimize tail calls to avoid findMember calls

Cache the member symbols for `Boolean.{||, &&}` per-run, rather
than look them up repeatedly.

Based on profiling the tail calls phase in the program below, which
was distilled by @rmacleod2 from the code generated by macros in
https://github.com/paytronix/utils-open/tree/release/2014/ernststavrosgrouper

Wall clock time went from 12s to 6.5s.

```scala
object Test {
    def a(): Option[String] = Some("a")

    def main(args: Array[String]) {
        a() match {
            case Some(b1) =>
        a() match {
            case Some(b2) =>
        a() match {
            case Some(b3) =>
        a() match {
            case Some(b4) =>
        a() match {
            case Some(b5) =>
        a() match {
            case Some(b6) =>
        a() match {
            case Some(b7) =>
        a() match {
            case Some(b8) =>
        a() match {
            case Some(b9) =>
        a() match {
            case Some(b10) =>
        a() match {
            case Some(b11) =>
        a() match {
            case Some(b12) =>
        a() match {
            case Some(b13) =>
        a() match {
            case Some(b14) =>
        a() match {
            case Some(b15) =>
        a() match {
            case Some(b16) =>
        a() match {
            case Some(b17) =>
        a() match {
            case Some(b18) =>
        a() match {
            case Some(b19) =>
        a() match {
            case Some(b20) =>
                println("yay")
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
    }
}
```

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