These issues were found by Coverity static analysis tool

Error: DEADCODE (CWE-561): [#def3]
gd-2.0.35/gd.c:3494: cond_cannot_single: Condition "dx == 0L", taking false branch. Now the value of "dx" cannot be equal to 0.
gd-2.0.35/gd.c:3502: cannot_single: At condition "dx == 0L", the value of "dx" cannot be equal to 0.
gd-2.0.35/gd.c:3502: dead_error_condition: The condition "dx == 0L" cannot be true.
gd-2.0.35/gd.c:3502: dead_error_line: Execution cannot reach this expression "dy == 0L" inside statement "if (dx == 0L && dy == 0L){
...".

Error: DEADCODE (CWE-561): [#def4]
gd-2.0.35/gd.c:1085: cond_cannot_single: Condition "dx == 0", taking false branch. Now the value of "dx" cannot be equal to 0.
gd-2.0.35/gd.c:1097: cannot_single: At condition "dx == 0", the value of "dx" cannot be equal to 0.
gd-2.0.35/gd.c:1097: dead_error_condition: The condition "dx == 0" cannot be true.
gd-2.0.35/gd.c:1097: dead_error_line: Execution cannot reach this expression "dy == 0" inside statement "if (dx == 0 && dy == 0){
  ...".


diff -up gd-2.0.35/gd.c.sa1 gd-2.0.35/gd.c
--- gd-2.0.35/gd.c.sa1	2012-12-05 16:23:09.289667430 +0100
+++ gd-2.0.35/gd.c	2012-12-05 16:30:41.634854587 +0100
@@ -1094,11 +1094,6 @@ BGD_DECLARE(void) gdImageLine (gdImagePt
     {
       /* More-or-less horizontal. use wid for vertical stroke */
       /* Doug Claar: watch out for NaN in atan2 (2.0.5) */
-      if ((dx == 0) && (dy == 0))
-	{
-	  wid = 1;
-	}
-      else
 	{
 	  /* 2.0.12: Michael Schwartz: divide rather than multiply;
 	     TBB: but watch out for /0! */
@@ -3490,6 +3485,12 @@ static void gdImageAALine (gdImagePtr im
 	dx = x2 - x1;
 	dy = y2 - y1;
 
+	if (dx == 0 && dy == 0) {
+		/* TBB: allow setting points */
+		gdImageSetAAPixelColor(im, x1, y1, col, 0xFF);
+		return;
+	}
+
 	/* Axis aligned lines */
 	if (dx == 0) {
 		gdImageVLine(im, x1, y1, y2, col);
@@ -3499,12 +3500,7 @@ static void gdImageAALine (gdImagePtr im
 		return;
 	}
 
-	if (dx == 0 && dy == 0) {
-		/* TBB: allow setting points */
-		gdImageSetAAPixelColor(im, x1, y1, col, 0xFF);
-		return;
-	}
-	else { 
+	{ 
 	    double ag; 
 	    if (abs(dy) < abs(dx))  
 		ag  = cos (atan2 (dy, dx));