vim-patch:8.0.1491: the minimum width of the popup menu is hard coded

Problem:    The minimum width of the popup menu is hard coded.
Solution:   Add the 'pumwidth' option. (Christian Brabandt, James McCoy,
            closes vim/vim#2314)
a8f04aa275

src/nvim/options.lua

@@ -1822,6 +1822,13 @@ return {
       varname='p_ph',
       defaults={if_true={vi=0}}
     },
+    {
+      full_name='pumwidth', abbreviation='pw',
+      type='number', scope={'global'},
+      vi_def=true,
+      varname='p_pw',
+      defaults={if_true={vi=0}}
+    },
     {
       full_name='pumblend', abbreviation='pb',
       type='number', scope={'global'},