This moves the installation of shipped source files from large
CMakeLists.txt lists to zig build recursive directory installation.
On my computer a cmake `make install` takes 2.4 seconds even when it has
to do nothing, and prints a lot of unnecessary lines to stdout that say
"up-to-date: [some file it is installing]".
After this commit, the default output of `make` is down to 1
second, and it does not print any junk to stdout. Further, a `make
install` is no longer required and `make` is sufficient.
This closes#2874.
It also closes#2585. `make` now always invokes `zig build` for
installing files and libuserland.a, and zig's own caching system makes
that go fast.
Before, allocator implementations had to provide `allocFn`,
`reallocFn`, and `freeFn`.
Now, they must provide only `reallocFn` and `shrinkFn`.
Reallocating from a zero length slice is allocation, and
shrinking to a zero length slice is freeing.
When the new memory size is less than or equal to the
previous allocation size, `reallocFn` now has the option
to return `error.OutOfMemory` to indicate that the allocator
would not be able to take advantage of the new size.
For more details see #1306. This commit closes#1306.
This commit paves the way to solving #2009.
This commit also introduces a memory leak to all coroutines.
There is an issue where a coroutine calls the function and it
frees its own stack frame, but then the return value of `shrinkFn`
is a slice, which is implemented as an sret struct. Writing to
the return pointer causes invalid memory write. We could work
around it by having a global helper function which has a void
return type and calling that instead. But instead this hack will
suffice until I rework coroutines to be non-allocating. Basically
coroutines are not supported right now until they are reworked as
in #1194.
