Add at least one pitch to each cell in BloatChannel profile.

* Change: In Etesian::BloatChannel, when two DFFs are side by side, if
    they are not separated by at least one pitch, the track avoid
    mechanism will not be able to work. Hence the minimal one pitch.

etesian/src/BloatCells.cpp

@@ -176,7 +176,7 @@ namespace Etesian {
     if (termRatio > 0.5) {
       return vpitch * (2*terminals + extra - xsize);
     }
-    return 0;
+    return 1;
 
  // if (xsize < 4) return vpitch*4;
  // if (xsize < 6) return vpitch*2;