REPL 'last change' time-stamp should be taken from start of reload

[ohad]

Steps to Reproduce

Take a file that takes idris2 a while to type-check, say Foo.idr.
While idris2 is type-checking, make a change in the file and save before idris2 finishes.
Reload the file.

Expected Behavior

Main> :r
1/1 Building Main (Foo.idr)
Main> 

Observed Behavior

Main> :r
Main> 

I think this is because the timestamp on the last change to this file is taken after type-checking finishes, and it should be taken before type-checking starts.