patch 8.1.1708: Coverity warns for using uninitialized variable

Problem:    Coverity warns for using uninitialized variable.
Solution:   Set the start col when col is set.
diff --git a/src/beval.c b/src/beval.c
index 1939646..3dd9b67 100644
--- a/src/beval.c
+++ b/src/beval.c
@@ -72,6 +72,7 @@
 		    }
 
 		    col = vcol2col(wp, lnum, col);
+		    scol = col;
 
 		    if (VIsual_active
 			    && wp->w_buffer == curwin->w_buffer
@@ -95,6 +96,7 @@
 			lbuf = vim_strnsave(lbuf + spos->col, len);
 			lnum = spos->lnum;
 			col = spos->col;
+			scol = col;
 		    }
 		    else
 		    {