Improve apply-patches

The default installation of patches/apply-patches uses a hardcoded
value, which will be incorrect in most cases, so we will query python
instead.

The messages during installation are misleading:

  Patching /usr/lib/python3.6/site-packages with cinderlib-bug-1856556.patch
  Patch already applied, skipping
  Patching /usr/lib/python3.6/site-packages with cinderlib-bug-1873312.patch
  1 out of 1 hunk FAILED
  1 out of 1 hunk FAILED

So it's hard to tell if the FAILED messages should have been a failure
or not.

So we update the script to have a clearer output:

  Checking if cinderlib-bug-1856556.patch is already present in /home/geguileo/code/reuse-cinder-drivers/ember/.venv3/lib/python3.7/site-packages
      Patch already applied, skipping
  Checking if cinderlib-bug-1873312.patch is already present in /home/geguileo/code/reuse-cinder-drivers/ember/.venv3/lib/python3.7/site-packages
      Patch not present, applying it

patches/apply-patches

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 set -ev
-PACKAGES_DIR=${1:-/usr/lib/python2.7/site-packages}
+PACKAGES_DIR=${1:-`python -m site --user-site`}
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 # Use a manual list instead of file listing in case we have a required order
 # Generated to avoid including tests using:
@@ -12,12 +12,12 @@ declare -a PATCHES=("cinderlib-bugs-1849339-1849828.patch"
                     "cinderlib-bug-1873312.patch")
 
 for patch_file in "${PATCHES[@]}"; do
-   echo "Patching $PACKAGES_DIR with $patch_file"
    PATCH_FILE="$SCRIPT_DIR/$patch_file"
-   # Check if already applied
-   if ! patch -R -p0 -s -f --dry-run -d $PACKAGES_DIR <$PATCH_FILE; then
+   echo "Checking if $patch_file is already present in $PACKAGES_DIR"
+   if ! patch -R -p0 -s -f --dry-run -d $PACKAGES_DIR >/dev/null <$PATCH_FILE; then
+     echo -e "\tPatch not present, applying it"
      patch -p0 -N --silent -d $PACKAGES_DIR <$PATCH_FILE
    else
-     echo "Patch already applied, skipping"
+     echo -e "\tPatch already applied, skipping"
    fi
 done