* charset.c: Fix file descriptor leaks and errno issues.

* charset.c: Fix file descriptor leaks and errno issues.

Include <errno.h>.
(load_charset_map_from_file): Don't leak file descriptor on error.
Use plain record_xmalloc since the allocation is larger than
MAX_ALLOCA; that's simpler here.  Simplify test for exhaustion
of entries.
* eval.c (record_unwind_protect_nothing):
* fileio.c (fclose_unwind):
New functions.
* lread.c (load_unwind): Remove.  All uses replaced by fclose_unwind.
The replacement doesn't block input, but that no longer seems
necessary.