[gaxis] do not paint first and last tick twice

If position of first or last tick does not match exactly visible axis range, extra first and extra last tick was painted.
While such matching can suffer from float arithmetic uncertanty,
on some platforms extra ticks was painted and on others not.
This was actually main reason for light variation of PS file size on different platforms.

Now simply do not paint first and last tick again in no case.

Author: linev

graf2d/graf/src/TGaxis.cxx

@@ -1732,7 +1732,8 @@ void TGaxis::PaintAxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t yma
          if ((!optionNoopt || optionInt) && axis_length0) {
             nticks0 = Int_t(axis_length0/dxtick);
             if (nticks0 > 1000) nticks0 = 1000;
-            for (k=0; k<=nticks0; k++) {
+            xtick0 -= dxtick; // skip first major tick which already was drawn
+            for (k=1; k<=nticks0; k++) {
                ltick = 2;
                if (k%nn3 == 0) ltick = 1;
                if (k%nn2 == 0) ltick = 0;
@@ -1776,7 +1777,8 @@ void TGaxis::PaintAxis(Double_t xmin, Double_t ymin, Double_t xmax, Double_t yma
          if ((!optionNoopt || optionInt) && axis_length1) {
             nticks1 = int(axis_length1/dxtick);
             if (nticks1 > 1000) nticks1 = 1000;
-            for (k=0; k<=nticks1; k++) {
+            xtick1 += dxtick; // skip last major tick which was already drawn
+            for (k=1; k<=nticks1; k++) {
                ltick = 2;
                if (k%nn3 == 0) ltick = 1;
                if (k%nn2 == 0) ltick = 0;