Revert "Makefile: clean out settings.mk"

This reverts commit 7982148.

Signed-off-by: Martin Povišer <[email protected]>

Author: povik

flow/Makefile

@@ -1,3 +1,7 @@
+# settings.mk is not under source control. Put variables into this
+# file to avoid having to adding the to the make command line.
+-include settings.mk
+
 # ==============================================================================
 # Uncomment or add the design to run
 # ==============================================================================