[win] Refactor GlobalLock/Unlock() calls w/HglobalLock class

[win] Add compatibility to paste 1bpp and 4bpp bitmaps

[win] Fix reading top-down 8bpp DIBs

Adopt 602cf09 solution for 8 bpp
images too.

Fix missing cstdint includes

[osx] Fix memory leaks using -fobjc-arc correctly

The -fobjc-arc flags must be specified for the compiler, not in the
linker. This generates a lot of memory leaks when we copy content into
the clipboard (just testing copy/put_image examples with a for loop to
repeat the action can easily show this leak).

This might be the reason of some memory leaks reported on the macOS
port of Aseprite: aseprite/aseprite#4251

Use target_sources & target_compile_definitions in CMake file

Add hmodule for WinXP support to auto-free the loaded dll + check suc…

…cess of each step

[win] Fix bug pasting 8bpp images

Fixes a bug copying 8bpp images (e.g. from YY-CHR program).
Regression introduced in a834ed5

Related issues:
aseprite/aseprite#4029
https://community.aseprite.org/t/6842

Fix crash accessing 24bpp image data with specific row sizes

Fixes aseprite/aseprite#2979

get_data_from_selection_owner() needs m_lock mutex locked