Prevent hanging in next-single-char-property-change

* src/textprop.c (Fnext_single_char_property_change): Clarify in
the doc string the behavior when LIMIT is past the end of OBJECT.
Stop the search when position gets to end of buffer, for when LIMIT
is beyond that.  (Bug#40000)
1 job for master in 55 minutes and 52 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #5873
test-all

00:55:52

 
Name Stage Failure
failed
test-all Test
make[1]: Leaving directory '/builds/emacs/emacs/lisp'
make -C test check-expensive
make[1]: Entering directory '/builds/emacs/emacs/test'
rm -f ./*.tmp
make[2]: Entering directory '/builds/emacs/emacs/test'
make[3]: Entering directory '/builds/emacs/emacs/test'
ELC lisp/net/tramp-tests.elc
GEN lisp/net/tramp-tests.log
ERROR: Job failed: exit code 137