patch 8.0.1687: 64 bit compiler warnings

Problem:    64 bit compiler warnings.
Solution:   change type, add type cast. (Mike Williams)

src/terminal.c

@@ -3400,7 +3400,7 @@ static VTermParserCallbacks parser_fallbacks = {
    static void *
vterm_malloc(size_t size, void *data UNUSED)
{
    return alloc_clear(size);
    return alloc_clear((unsigned) size);
}

    static void
@@ -4016,9 +4016,9 @@ get_separator(int text_width, char_u *fname)
    int	    fname_size;
    char_u  *p = fname;
    int	    i;
    int	    off;
    size_t  off;

    textline = alloc(width + STRLEN(fname) + 1);
    textline = alloc(width + (int)STRLEN(fname) + 1);
    if (textline == NULL)
	return NULL;

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    1687,
/**/
    1686,
/**/