cmd/compile: Budget for inlining is now 80 nodes, not 40

This comment was out of date since the bump to 80 done as the same time
as inlining transitive functions in:

  commit 77ccb16e
  Author: Russ Cox <rsc@golang.org>
  Date:   Tue Feb 24 12:19:01 2015 -0500

      cmd/internal/gc: transitive inlining

Adjust the comment at the top of the file accordingly.

Change-Id: Ia6d7397c874e3b85396e82dc9678e56aab9ad728
Reviewed-on: https://go-review.googlesource.com/40910Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/inl.go

@@ -11,7 +11,7 @@
 // making 1 the default and -l disable.  -ll and more is useful to flush out bugs.
 // These additional levels (beyond -l) may be buggy and are not supported.
 //      0: disabled
-//      1: 40-nodes leaf functions, oneliners, lazy typechecking (default)
+//      1: 80-nodes leaf functions, oneliners, lazy typechecking (default)
 //      2: early typechecking of all imported bodies
 //      3: allow variadic functions
 //      4: allow non-leaf functions , (breaks runtime.Caller)