BUILD: makefile: stop opening sub-shells for each and every command

BUILD: makefile: stop opening sub-shells for each and every command

We're spending ~8% of the total build time calling a shell to display
"CC" using the "echo" command! We don't really need this, as make also
knows a "$(info ...)" command to print a message. However there's a catch,
this command trims leading spaces, so we need to use an invisible space
using "$ ". Furthermore, in GNU make 3.80 and older, $(info) doesn't show
anything, so we only do that for 3.81 and above, older versions continue
to use echo.

This measurably speeds up build time especially at -O0 that developers
use most of the time for quick checks.