Use elc.eir.exe built by host cc for elc-* targets
Use elc.eir.exe built by host cc for elc-* targets

This speeds up the build on Mac.

shinh/elvm,ND-CSE-30151/elvm,shinh/elvm,shinh/elvm,shinh/elvm,shinh/elvm,shinh/elvm,shinh/elvm,shinh/elvm,ND-CSE-30151/elvm,ND-CSE-30151/elvm