patch 8.0.1041: bogus characters when indenting during visual-block append

Problem:    Bogus characters appear when indenting kicks in while doing a
            visual-block append.
Solution:   Recompute when indenting is done. (Christian Brabandt)

src/charset.c

@@ -1535,6 +1535,22 @@ skipwhite(char_u *q)
     return p;
 }
 
+/*
+ * getwhitecols: return the number of whitespace
+ * columns (bytes) at the start of a given line
+ */
+    int
+getwhitecols_curline()
+{
+    return getwhitecols(ml_get_curline());
+}
+
+    int
+getwhitecols(char_u *p)
+{
+    return skipwhite(p) - p;
+}
+
 /*
  * skip over digits
  */