add major/minor/makedev on apple OSes

[SteveLauC]

This impl corresponds to the macros in sys/types.h:

#define major(x)        ((int32_t)(((u_int32_t)(x) >> 24) & 0xff))
#define minor(x)        ((int32_t)((x) & 0xffffff))
#define makedev(x, y)    ((dev_t)(((x) << 24) | (y)))

[rust-highfive]

r? @Amanieu

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[JohnTitor]

@bors r+

[bors]

📌 Commit 11a1ffe has been approved by JohnTitor

It is now in the queue for this repository.

[bors]

⌛ Testing commit 11a1ffe with merge 198beb0...

[bors]

☀️ Test successful - checks-actions, checks-cirrus-freebsd-12, checks-cirrus-freebsd-13, checks-cirrus-freebsd-14
Approved by: JohnTitor
Pushing 198beb0 to master...