patch 8.1.0100: terminal debugger: error when setting a watch point

Problem:    Terminal debugger: error when setting a watch point.
Solution:   Don't try defining a sign for a watch point.

runtime/pack/dist/opt/termdebug/plugin/termdebug.vim

@@ -863,6 +863,11 @@ endfunc
" Handle setting a breakpoint
" Will update the sign that shows the breakpoint
func s:HandleNewBreakpoint(msg)
  if a:msg !~ 'fullname='
    " a watch does not have a file name
    return
  endif

  let nr = substitute(a:msg, '.*number="\([0-9]\)*\".*', '\1', '') + 0
  if nr == 0
    return

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    100,
/**/
    99,
/**/