patch 8.1.1579: dict and list could be GC'ed while displaying error

Problem:    Dict and list could be GC'ed while displaying error in a timer.
            (Yasuhiro Matsumoto)
Solution:   Block garbage collection when executing a timer.  Add
            test_garbagecollect_soon(). Add "no_wait_return" to
            test_override(). (closes vim#4571)

patch 8.1.1578: MS-Windows: pathdef.c should depend on build options

Problem:    MS-Windows: pathdef.c should depend on build options.
Solution:   Generate pathdef.c in the object directory.  Fix dependencies.
            (Ken Takata, closes vim#4565)

patch 8.1.1577: command line redrawn for +arabic without Arabic chara…

…cters

Problem:    Command line redrawn for +arabic without Arabic characters.
            (Dominique Pelle)
Solution:   Check if there actually are any Arabic characters.  Do redraw
            after displaying incsearch. (closes vim#4569)

patch 8.1.1576: compiler warning for unused argument

Problem:    Compiler warning for unused argument.
Solution:   Add "UNUSED" annotation. (Dominique Pelle, closes vim#4570)

patch 8.1.1575: callbacks may be garbage collected

Problem:    Callbacks may be garbage collected.
Solution:   Set reference in callbacks. (Ozaki Kiichi, closes vim#4564)

patch 8.1.1574: tabpage option not yet implemented for popup window

Problem:    Tabpage option not yet implemented for popup window.
Solution:   Implement tabpage option, also for popup_getoptions().

patch 8.1.1573: textprop test fails if screenhots do not work

Problem:    Textprop test fails if screenhots do not work.
Solution:   Add check for screenhots working.

patch 8.1.1572: compiler warnings with tiny build

Problem:    Compiler warnings with tiny build. (Tony Mechelynck)
Solution:   Add #ifdef.

patch 8.1.1571: textprop highlight starts too early if just after a tab

Problem:    textprop highlight starts too early if just after a tab.
Solution:   Check if still drawing a previous character. (closes vim#4558)

patch 8.1.1570: icon signs not displayed properly in the number column

Problem:    Icon signs not displayed properly in the number column.
Solution:   Display them properly. (Yegappan Lakshmanan, closes vim#4559)