Make minor fixes to output_env.sh after review
Make minor fixes to output_env.sh after review

A number of clean-up improvements following review.
 * removal of redundant `` quotes
 * removal of non-portable echo "\n", in favour of additional echo commands
 * change to use of uname to detemine if the platform is Linux or not
 * revised formatting of output
 * change to dpkg-query from dpkg to find installed libasan variants

Co-Authored-By: Gilles Peskine <f829db02715a0ea34b7c8e25097dae9e3517e831@arm.com>
Signed-off-by: Simon Butcher <7d82bfad2c24fb08ce98cf6cb1497c261bdb093f@arm.com>

Mbed-TLS/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls