Some changes to closures:

Some changes to closures:
- Tightening of the entry sequence.
- Closure generation by copying a pattern made by the compiler.
- Add ability to set breakpoints in closures' internal entry points.
- Add CLOSURE_PATTERN_LINKAGE_KIND used by the new patterns.

Align compiled code blocks on floating-point boundaries so that the
compiler can pad to guarantee that embedded floating-point numbers
(and closure patterns, copied using floating-point instructions on the
hppa) are aligned correctly.