* nt/inc/ms-w32.h (strerror): Redirect to sys_strerror after
including <string.h>, to prevent the linker from thinking it
should be imported from some DLL.  Reported by Richard Copley
<rcopley@gmail.com>.

* src/w32.c: Remove now unneeded prototype of sys_strerror.

The info returned from `garbage-collect` is really handy to
track the evolution of the heap size, but sadly it's available only
at the cost of running a full GC, which has two big downsides:
it's slow, it affects what we're measuring, and it can't be used
in `post-gc-hook`.
So, this patch makes it available without running the GC.

* src/alloc.c (Fgarbage_collect_heapsize): New function, extracted from
`Fgarbage_collect`.
(Fgarbage_collect): Use it.
(syms_of_alloc): defsubr it.

* doc/lispref/internals.texi (Garbage Collection): Extract
documentation for it from that of `garbage-collect`.

* src/pdumper.c (pdumper_set_emacs_execdir):
Don’t use basename; simply use the pointer we already have.
If we ever need a basename-like function in the future, we should
use Gnulib’s basename-lgpl module, as POSIX basename modifies its
argument string and is incompatible with glibc/Android basename; see
<https://www.gnu.org/software/gnulib/manual/html_node/basename.html>.

* src/indent.c (Fvertical_motion): Fix vertical cursor motion when
a screen line begins with an overlay string.  (Bug#80223)

* src/window.c (Fwindow_cursor_info): Return canonical character width
when on stretch glyph and `x-stretch-cursor' is nil.  (Bug#80211)

* src/nsterm.m (ns_select_1): Return thread_select if current
thread is not the main thread or timeout is zero; otherwise call
'thread_select' with a minimal timeout to allow other Lisp
threads to run.  (Bug#80110, Bug#80112)