tools: fix install.sh for non-Nix systems

Change-Id: Id3aa846255129d90be22bce2aa38d468d78d816c
Reviewed-on: https://gerrit.hackerspace.pl/c/hscloud/+/1533
Reviewed-by: q3k <q3k@hackerspace.pl>
diff --git a/tools/install.sh b/tools/install.sh
index 04b4f79..38b7422 100755
--- a/tools/install.sh
+++ b/tools/install.sh
@@ -29,18 +29,18 @@
 
     local path_missing=""
     local path="$(hscloud::workspace_location)/bazel-bin/tools"
-    if [[ ":$PATH:" == *":$path:"* ]]; then
+    if [[ ":$PATH:" != *":$path:"* ]]; then
         path_missing="$path"
     fi
     local path="$(hscloud::workspace_location)/bazel-bin/cluster/tools"
-    if [[ ":$PATH:" == *":$path:"* ]]; then
+    if [[ ":$PATH:" != *":$path:"* ]]; then
         if [ -z "$path_missing" ]; then
             path_missing="$path"
         else
             path_missing="$path_missing:$path"
         fi
     fi
-    if [ -z "$path_missing" ]; then
+    if [ ! -z "$path_missing" ]; then
         echo "Tools built correctly, but your PATH should be updated to access them:">&2
         echo '   PATH="$PATH:'$path_missing'"'
         echo 'Add the above line to your shell profile, or source env.sh from the root of hscloud.'