recognise wxallowed as a keyword

don't highlight device-node errors, the fsDeviceError regex trips on
our duid format in /etc/fstab

Index: runtime/syntax/fstab.vim
--- runtime/syntax/fstab.vim.orig
+++ runtime/syntax/fstab.vim
@@ -34,7 +34,7 @@ syn match fsOperator /[,=:#]/
 
 " Device
 syn cluster fsDeviceCluster contains=fsOperator,fsDeviceKeyword,fsDeviceError
-syn match fsDeviceError /\%([^a-zA-Z0-9_\/#@:\.-]\|^\w\{-}\ze\W\)/ contained
+"syn match fsDeviceError /\%([^a-zA-Z0-9_\/#@:\.-]\|^\w\{-}\ze\W\)/ contained
 syn keyword fsDeviceKeyword contained none proc linproc tmpfs devpts devtmpfs sysfs usbfs
 syn keyword fsDeviceKeyword contained LABEL nextgroup=fsDeviceLabel
 syn keyword fsDeviceKeyword contained UUID nextgroup=fsDeviceUUID
@@ -221,7 +221,7 @@ syn match fsOptionsKeywords contained /\<\%(prjjquota\
 syn keyword fsOptionsKeyWords contained gc_merge nogc_merge disable_roll_forward no_heap disable_ext_identify inline_xattr noinline_xattr inline_data noinline_data inline_dentry noinline_dentry flush_merge fastboot extent_cache noextent_cache data_flush offusrjquota offgrpjquota offprjjquota test_dummy_encryption checkpoint_merge nocheckpoint_merge compress_chksum compress_cache inlinecrypt atgc
 
 " Options: ffs
-syn keyword fsOptionsKeyWords contained noperm softdep
+syn keyword fsOptionsKeyWords contained noperm softdep wxallowed
 
 " Options: gfs2
 syn match fsOptionsKeywords contained /\<\%(lockproto\|locktable\)=/ nextgroup=fsOptionsString