vim-patch:8.0.0431 (#7908)

vim-patch:8.0.0431: 'cinoptions' cannot set indent for extern block
Problem:    'cinoptions' cannot set indent for extern block.
Solution:   Add the "E" flag in 'cinoptions'. (Hirohito Higashi)
7720ba8599

src/nvim/buffer_defs.h

@@ -718,6 +718,7 @@ struct file_buffer {
   int b_ind_hash_comment;
   int b_ind_cpp_namespace;
   int b_ind_if_for_while;
+  int b_ind_cpp_extern_c;
 
   linenr_T b_no_eol_lnum;       /* non-zero lnum when last line of next binary
                                  * write should not have an end-of-line */