This is a mostly cosmetical commit, in the sense it doesn't change the contents
of any package, but reorganizes the overall Nixpkgs expressions.
Terminal emulators are an ubiquitous tool for any Unix user; even the beginners
are routinely familiarized to it. And, manifestly, there are many
implementations of terminal emulators out there, from those traditionally made
in C and C++ to those written in Haskell and Go.
Terminal emulators deserve more highlight. This commit does that by creating a
category for them.
During iterm2's build, xcodebuild invokes $LD and passes it options such
as -isysroot. These options are intended for the linker driver (clang),
not for the linker directly. ld64 ($LD) does not recognize these
options, causing iterm2's build to fail.
Set $LD to $CC (clang) as intended, making iterm2's build succeed.