treewide: {target->host}Platform non-compiler-ish packages

[ghost]

This causes no rebuilds; eval (at least for the hydra jobset) is unaffected.

Description of changes

stdenv.targetPlatform really shouldn't be used by software that doesn't read, write, or manipulate executables.

I reviewed all uses of targetPlatform outside of pkgs/development/compilers and pkgs/stdenv, and replaced those which weren't involved in something which fits these criteria. Nearly all of them appear to have arisen from confusion about the meaning of host and target.

Findings

Here are the categories covering all the legitimate uses of stdenv.targetPlatform that I was able to find:

• assemblers and compilers (but not interpreters or JITs) which emit machine code
• debuggers and fuzzers (host!=target useful only if host.canExecute target)
• tools for manipulating executables (bintools, patchelf)
• emulators that need target binaries/firmware/bootloaders at emulator build time
• awkward exceptions:
  • gobject-introspection (technically a compiler, but does not emit machine code)
  • software which uses target-platform paths at build time
    • pkg-config (probably the only legit example)
    • s6-rc-compile, s6-linux-init (I may try to upstream a fix for this)
    • a few poorly-designed build managers

After this PR, there are only 65 files in pkgs but outside of pkgs/development/compilers which mention targetPlatform. Filtering out pkgs/development/tools/build-managers/, pkgs/top-level/, pkgs/stdenv, and pkgs/build-support brings the number down to 35.

Motivation

This PR is part of work towards a theory that the vast majority of nixpkgs ought to be oblivious to targetPlatform, and that we will all be happier that way.

• Packages should have to opt-into target sensitivity #263640

[Artturin]

gobject-introspection compiles code, but via an emulator because it's not a cross-compiler 😩

[ghost]

• This is a treewide PR at high risk of accruing merge conflicts.
• This PR has one non-author approval.
• Ofborg has verified that this causes zero rebuilds.
  • I have also confirmed that it does not affect eval for pkgs.tests.cross.sanity

Considering all of the above, I am going to self-merge this PR.