Enhance the output_env.sh script
Enhance the output_env.sh script

This commit adds additional information to the output_env.sh script of:
  * Linux distribution version (if available)
  * GDB version (if available)

It also makes some information clearer:
  * the type of OpenSSL/GNUTLS version (legacy/default/next)
  * and whether certain versions are not installed, or not configured

And it simplifies the error messages for absent tools.

Signed-off-by: Simon Butcher <7d82bfad2c24fb08ce98cf6cb1497c261bdb093f@arm.com>

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