Review: Remove long_u: memfile: Enable -Wconversion.

- Add memfile.c to converted files list.
- Fix conversion issues:
    * bhdr_T          : bh_page_count : int  -> unsigned.
    * bhdr_T          : bh_flags      : char -> unsigned.
    * mf_new()        : page_count    : int  -> unsigned.
    * mf_get()        : page_count    : int  -> unsigned.
    * mf_release()    : page_count    : int  -> unsigned.
    * mf_alloc_bhdr() : page_count    : int  -> unsigned.
    * mf_trans_add()  : page_count    : int  -> unsigned.
    * mf_put()        : flags         : int  -> unsigned.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 04ee0d7f55..f0062c22bd 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -41,6 +41,7 @@
  *  mf_get().
  */
 
+#include <assert.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <string.h>
@@ -2725,7 +2726,8 @@ static void ml_flush_line(buf_T *buf)
  */
 static bhdr_T *ml_new_data(memfile_T *mfp, int negative, int page_count)
 {
-  bhdr_T *hp = mf_new(mfp, negative, page_count);
+  assert(page_count >= 0);
+  bhdr_T *hp = mf_new(mfp, negative, (unsigned)page_count);
   DATA_BL *dp = (DATA_BL *)(hp->bh_data);
   dp->db_id = DATA_ID;
   dp->db_txt_start = dp->db_txt_end = page_count * mfp->mf_page_size;