Makefile: install frontends/verilog/verilog_location.h.

[Muxianesty]

What are the reasons/motivation for this change?

By installing Yosys includes with install-target we ultimately install frontends/ast/ast.h, which now includes frontends/verilog/verilog_location.h, yet verilog_location.h is not installed along with ast.h.

Explain how this is achieved.

frontends/verilog/verilog_location.h is specified as an explicit header file in Makefile to be installed at some prefix.

Make sure your change comes with tests. If not possible, share how a reviewer might evaluate it.

Just try to compile some C-code including frontends/ast/ast.h.

[widlarizer]

Sure, but are you including ast.h in your plugin? If so, why? Ideally, I'd make sure ast.h is never installed instead. In 72a0380 I've removed the comment telling people they should use it in their own HDL frontends, because it's a terrible idea. It now instead tells you it's just support code for the existing read_verilog frontend