Load dynamic fonts to memory on all platforms, to avoid locked files.

[bruvzg]

Fully load dynamic fonts to memory instead of streaming from the open file.

Should fix #23773.

Bugsquad edit: Likely closes #36971 as well.

[akien-mga]

For the reference, @reduz seems to agree with the technical change:

14:54 <Akien> reduz: WDYT about #44117 ? Was there technical reasons to go with streaming from opened files instead of loading into memory for DynamicFont? The latter could solve Windows users' pain with not being able to move fonts.
14:56 <Calinou> there was also another issue reported with a large amount of file handles being created and never freed
14:56 <Calinou> (on Linux)
14:56 <Calinou> each font size had its own file handle
14:57 <reduz> Akien: nowadays it probably makes no sense to stream them, to be honest
14:57 <reduz> everything has way too much memory

[bruvzg]

each font size had its own file handle

This is still true, each size use it's own FT_Face instance and multiple FT_Streams with the same file handle do not work reliably.
With the changes in this PR all font sizes will share the same memory buffer.

[Calinou]

This is still true, each size use it's own FT_Face instance and multiple FT_Streams with the same file handle do not work reliably.
With the changes in this PR all font sizes will share the same memory buffer.

I guess we can close #36971 as "not resolvable" then.

[bruvzg]

I guess we can close #36971 as "not resolvable" then.

Why? Loading fonts to memory should work for 3.2 in the same way (I'll make separate PR after testing this one), and will resolve it (file opened once per font and closed after loading).

[Calinou]

@bruvzg I see, I misunderstood your previous comment.

[bruvzg]

3.2 PR - #44160

[akien-mga]

The commit message still says "[WIP]", it might be good to amend it.

[bruvzg]

it might be good to amend it.

Done.

[akien-mga]

Thanks!