moving: use the correct formula for pushing the index forward

This helps to fix https://savannah.gnu.org/bugs/?51787

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Correction-by: David Lawrence Ramsey <pooka109@gmail.com>

src/move.c

@@ -70,8 +70,8 @@ size_t proper_x(const char *text, size_t leftedge, size_t column)
     size_t index = actual_x(text, column);
 
 #ifndef NANO_TINY
-    if (ISSET(SOFTWRAP) && text[index] == '\t' &&
-		column < leftedge + leftedge % tabsize)
+    if (ISSET(SOFTWRAP) && text[index] == '\t' && leftedge % tabsize != 0 &&
+			column < leftedge + tabsize)
 	index++;
 #endif