Make tools/min-env.sh portable

We had different issues here.

First, sort command used to sort variables and services names is
dependent on the local, so fix it to C to have consistent
results. C local is available on all systems.

Second, awk doesn't recognize \s escape char for space on OSX. This
resulted in indented check_required_vars calls being ignored. In fact,
all variables checked via indented check_required_vars calls (i.e. in
a fuction or conditional block) are actually *optional* variables, so
I changed the behavior to ignore those.

Change-Id: I6fc4cca9567cb712609d0fe0a20dfe21ed6df151
Closes-Bug: #1470683

tools/min-env.sh

@@ -6,6 +6,9 @@
 REAL_PATH=$(python -c "import os,sys;print os.path.realpath('$0')")
 cd "$(dirname "$REAL_PATH")/.."
 
+# Make sure sort produces the same output on all systems
+export LC_ALL=C
+
 DOC=docs/minimal-environment-vars.md
 DOCKERDIR="docker"
 # BASE and TYPE can be hard coded to centos and rdo since the required vars will always be the same
@@ -35,7 +38,7 @@ function find_vars {
     scripts=$(find ${img_location} -name *.sh | sort -t / -k 4)
 
     for script in $scripts; do
-        local vars=$(awk '/^\s*check_required_vars/,/([^\\]\s*$)/' $script)
+        local vars=$(awk '/^check_required_vars/,/([^\\] *$)/' $script)
         vars=$(echo "$vars" | sed 's/check_required_vars//' | sed 's/\\//g')
 
         if [ ! -z "$vars" ]; then