PDK should have a make timing equivalent

[RTimothyEdwards]

Expected Behavior

make timing generates liberty headers and creates the liberty libraries (as it does in the sky130 open PDK)

Actual Behavior

There is no make timing, and there are no liberty file headers.

Probably it is close to sufficient to just copy the timing script from sky130 PDK and add the build recipe to the Makefile. There is probably some process-dependent stuff in the script that needs to be modified.

@mithro

[proppy]

re-opening since we still need to add a make timing equivalent.

[tstrahler]

The Liberty files still do not contain any information about the individual cells. This makes the PDK basically unusable when working with commercial synth tools.