patch 8.2.0510: Coverity complains about using uninitialized variable

Problem:    Coverity complains about using uninitialized variable.
Solution:   Assign a value to "scol".  Move code inside NULL check.
diff --git a/src/beval.c b/src/beval.c
index 63aaf13..6b10a65 100644
--- a/src/beval.c
+++ b/src/beval.c
@@ -110,6 +110,8 @@
 			lbuf = vim_strnsave(lbuf, len);
 		    }
 		}
+		else
+		    scol = col;
 
 		if (winp != NULL)
 		    *winp = wp;