Feature request: Show parallel action names

[orenbenkiki]

Currently, Ninja holds off on writing the executed parallel action names until it has the complete output of some action - only then it prints the action name and its output. This makes the output nice to read (no mixing of output of different parallel actions).

However, this means that when actions take "a while" to run, one has no idea what ninja is actually running.

It would be nice if Ninja would print (in a single line) the (hopefully short) parallel action names, w/o showing the output from any of them (yet). When an action completes, it would clear the line and replace it with the name of the completed action, followed by its output, and followed by another line showing the updated list of parallel actions.

Something along the lines of how Rust cargo build shows the targets currently being built in parallel.

E.g.:

Building: A | B | C | D<cursor here>

Assume B finished first, Clear the line (\r followed by sufficient number of spaces followed by \r should work) and print:

B
... output of B ...
Building: A | C | D | E | F<cursor here>

[orgads]

Dup of #111

I started working on this, and posted my prototype, but nobody replied, so I didn't proceed.