patch 8.2.0953: spell checking doesn't work for CamelCased words

Problem:    Spell checking doesn't work for CamelCased words.
Solution:   Add the "camel" value in the new option 'spelloptions'.
            (closes #1235)
diff --git a/src/buffer.c b/src/buffer.c
index df92ecd..66b0050 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -2287,6 +2287,7 @@
     vim_regfree(buf->b_s.b_cap_prog);
     buf->b_s.b_cap_prog = NULL;
     clear_string_option(&buf->b_s.b_p_spl);
+    clear_string_option(&buf->b_s.b_p_spo);
 #endif
 #ifdef FEAT_SEARCHPATH
     clear_string_option(&buf->b_p_sua);