patch 8.2.2363: curpos() does not accept a string argument as before

Problem:    curpos() does not accept a string argument as before.
solution:   Make a string argument work again. (Yegappan Lakshmanan,
            closes #7690
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 61cca01..c9acd41 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -2767,7 +2767,8 @@
     }
     else if ((argvars[0].v_type == VAR_NUMBER ||
 					argvars[0].v_type == VAR_STRING)
-	    && argvars[1].v_type == VAR_NUMBER)
+	    && (argvars[1].v_type == VAR_NUMBER ||
+					argvars[1].v_type == VAR_STRING))
     {
 	line = tv_get_lnum(argvars);
 	if (line < 0)