Improve testsuite on windows

[fix][testsuite][vivado] Adjust Testsuite to !14

See merge request !15

Adjust testsuite to match mergerequest!14.

Testsuite passes on native Linux.

Add missing dir to Vivado clean targets

See merge request !14

makefile: make synthesis depend on source files

See merge request !13

When set to False, timing failures are ignored during implementation

This causes synthesis failures with verilog files that import
from each other.

For #117

The same unit can be defined in several files.  This is not (yet) considered
as an error as it happens in existing designs.

Now, only the first definition is considered.  A warning is emitted.
This reduces the possibility of non-deterministic behaviour.

Add VHDL library and PolarfireSOC device example to LiberoSOC in hdlmake

See merge request !9

Add VHDL Library support to GHDL Synthesis

See merge request !8

Add VHDL Library support to ISE

See merge request !7