Merge remote-tracking branch 'origin/master' into xc7mux

diff --cc Makefile
Simple merge

diff --cc techlibs/xilinx/synth_xilinx.cc
index 97464ffe48aabf86f7b3201b75942929dfa58c54,a293081f1825966dc164d26cb7fa7709d4f6efb0..e316c268e59ed21df4e0fe468ecec40766a7646a
--- 1/techlibs/xilinx/synth_xilinx.cc
--- 2/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@@ -274,10 -237,11 +274,14 @@@ struct SynthXilinxPass : public ScriptP
                                run("shregmap -tech xilinx -minlen 3", "(skip if '-nosrl')");
                        }
  
-                       run("techmap");
 +                      if (!nomux || help_mode)
 +                              run("techmap -map +/xilinx/cells_map.v");
 +
+                       if (!vpr || help_mode)
+                               run("techmap -map +/techmap.v -map +/xilinx/arith_map.v");
+                       else
+                               run("techmap -map +/techmap.v +/xilinx/arith_map.v -D _EXPLICIT_CARRY");
+ 
                        run("opt -fast");
                }