Fixes #61 and #62.
The `ARRAY-HAS-FILL-POINTER-P` and `ARRAY-DISPLACEMENT` functions are
declared inline and the compiler tries to constant-fold these inlined
functions operating on simple arrays.
Thus don't allow the compiler to constant-fold calls to
`%ARRAY-FILL-POINTER-P`. This is normally protected by a call to
`ARRAY-HEADER-P`, but when it's inlined, the compiler tries to
constant-fold `%ARRAY-FILL-POINTER-P` on an array without such a slot.
Likewise `ARRAY-DISPLACEMENT` calls `%ARRAY-DISPLACED-P`,
`%ARRAY-DATA-VECTOR`, and `%ARRAY-DISPLACEMENT`, and the calls are
protected by `ARRAY-HEADER-P`. So don't constant-fold these either.
Maybe we could also make CONSTANT-FOLD-CALL be smarter about this?
* Remove flushable from these ref-trans methods.
* Add tests from the bug reports.