Fall back to the absolute path for fstrim if needed

fstrim is usually in /usr/sbin, but /usr/sbin might not be in $PATH.
Use /usr/sbin/fstrim if this is the case.

Author: ArrayBolt3

qubes-rpc/post-install.d/95-fstrim.sh

@@ -5,5 +5,11 @@
 # only run if storage is persistent
 if [ -f /run/qubes/persistent-full ]
 then
-    fstrim -av
+    if command -v fstrim >/dev/null; then
+      fstrim -av
+    else
+      # /usr/sbin might not be in $PATH, fall back to the absolute path
+      # if necessary
+      /usr/sbin/fstrim -av
+    fi
 fi