versions.txt: nicer output

if YOSYS_EXE is empty, log it with iffy code. This avoids
-V being passed to bash and strange error messages appearing.

If YOSYS_EXE is non-empty, log error silently into versions.txt
as versions.txt goes into the make issue report and the actual output
from this command will not be part of the make issue

Signed-off-by: Øyvind Harboe <[email protected]>

Author: oharboe

flow/Makefile

@@ -184,9 +184,9 @@ $(foreach block,$(BLOCKS),$(eval $(WORK_HOME)/results/$(PLATFORM)/$(DESIGN_NICKN
 .PHONY: versions.txt
 versions.txt:
 	mkdir -p $(OBJECTS_DIR)
-	@echo "yosys $(shell $(YOSYS_EXE) -V 2>&1)" > $(OBJECTS_DIR)/$@
-	@echo "openroad $(shell $(OPENROAD_EXE) -version 2>&1)" >> $(OBJECTS_DIR)/$@
-	@echo "klayout $(shell $(KLAYOUT_CMD) -zz -v 2>&1)" >> $(OBJECTS_DIR)/$@
+	@echo "yosys $(if $(YOSYS_EXE),$(shell $(YOSYS_EXE) -V 2>&1),not available)" > $(OBJECTS_DIR)/$@
+	@echo "openroad $(if $(OPENROAD_EXE),$(shell $(OPENROAD_EXE) -version 2>&1),not available)" >> $(OBJECTS_DIR)/$@
+	@echo "klayout $(if $(KLAYOUT_CMD),$(shell $(KLAYOUT_CMD) -zz -v 2>&1),not available)" >> $(OBJECTS_DIR)/$@
 
 # Pre-process libraries
 # ==============================================================================