Add script to print build environment info. (#539)

* Add script to print build environment info.

The new script is also included in:
- all.sh
- basic-build-test.sh

* Tidy up environment reporting script.

Changes include:
- making the echo calls portable
- removing unnecessary brackets
- using more efficient checks for the existance of commands
- correcting typos and copyright year

* Update references to output_env.sh

tests/scripts/basic-build-test.sh

@@ -39,6 +39,10 @@ fi
 CONFIG_H='include/mbedtls/config.h'
 CONFIG_BAK="$CONFIG_H.bak"
 
+# Step 0 - print build environment info
+scripts/output_env.sh
+echo
+
 # Step 1 - Make and instrumented build for code coverage
 export CFLAGS=' --coverage -g3 -O0 '
 make clean