A recent change to libimobiledevice bumped the constraint on libusbmuxd to >= version 1.1.0. The current usbmuxd homebrew package is version 1.0.10.
As a result, homebrew --HEAD installs of libimobiledevice no longer build without a --HEAD install of usbmuxd.
Until the usbmuxd homebrew formula is updated, a workaround is to install it at HEAD:
brew update
brew uninstall --ignore-dependencies libimobiledevice
brew uninstall --ignore-dependencies usbmuxd
brew install --HEAD usbmuxd
brew install --HEAD libimobiledevice
You can track progress on this issue on flutter/flutter#22595.