Rewrite clean-all.sh to use the top-level Makefile (#287)
Rewrite clean-all.sh to use the top-level Makefile (#287)

This commit refactors the //clean-all.sh script to delegate the actual
build functionality to the //Makefile script.

Besides simplifying the script and removing duplicated information about
directories to be built, this also adds support of the
Emscripten/WebAssembly builds into clean-all.sh.

This commit contributes to the Emscripten/WebAssembly migration effort,
as tracked by #177.
GoogleChromeLabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector,googlechromelabs/chromeos_smart_card_connector,GoogleChromeLabs/chromeos_smart_card_connector