Fix c/cpp mapping to wrap lines in #if 0/#endif

Use `x` mapping so that the mapping does not also get enabled in select
mode.

after/ftplugin/c.lua

@@ -1,2 +1,2 @@
 local opts = { buffer = true, remap = false, silent = true }
-vim.keymap.set('v', '0', ':PreProcIfWrap<CR>', opts)
+vim.keymap.set('x', '0', ':PreProcIfWrap<CR>', opts)

after/ftplugin/cpp.lua

@@ -2,5 +2,4 @@ vim.opt.commentstring = '//%s'
 vim.opt.matchpairs:append('<:>')
 
 local opts = { buffer = true, remap = false, silent = true }
--- vim.keymap.set('n', '0', ':PreProcIfWrap<CR>', opts)
-vim.keymap.set('v', '0', ':PreProcIfWrap<CR>', opts)
+vim.keymap.set('x', '0', ':PreProcIfWrap<CR>', opts)