patch 8.2.3914: various spelling mistakes in comments

Problem:    Various spelling mistakes in comments.
Solution:   Fix the mistakes. (Dominique Pellé, closes #9416)
diff --git a/src/clipboard.c b/src/clipboard.c
index c0c21ae..38596f5 100644
--- a/src/clipboard.c
+++ b/src/clipboard.c
@@ -567,7 +567,7 @@
 	return;
 
     p = ScreenLines + LineOffset[row];
-    // Correct for starting in the right halve of a double-wide char
+    // Correct for starting in the right half of a double-wide char
     if (enc_dbcs != 0)
 	col -= dbcs_screen_head_off(p, p + col);
     else if (enc_utf8 && p[col] == 0)
@@ -1030,7 +1030,7 @@
     if (row2 > clip_star.max_row)
 	row2 = clip_star.max_row;
 #endif
-    // correct starting point for being on right halve of double-wide char
+    // correct starting point for being on right half of double-wide char
     p = ScreenLines + LineOffset[row1];
     if (enc_dbcs != 0)
 	col1 -= (*mb_head_off)(p, p + col1);
@@ -1140,7 +1140,7 @@
 									bufp);
 			}
 		    }
-		    // Skip right halve of double-wide character.
+		    // Skip right half of double-wide character.
 		    if (ScreenLines[off + i + 1] == 0)
 			++i;
 		}