Merge branch 'mbedtls-2.16' into baremetal

* mbedtls-2.16:
  test: Always use `make clean` by itself
  list-symbols.sh: if the build fails, print the build transcript
  Document "check-names.sh -v"
  all.sh: invoke check-names.sh in print-trace-on-exit mode
  Print a command trace if the check-names.sh exits unexpectedly
  Only use submodule if present
  Update change log
  Reword ssl_conf_max_frag_len documentation for clarity
  Ignore more generated files: seedfile, apidoc
  Improve .gitignore grouping and documentation
  Generate tags for Vi, for Emacs and with Global

scripts/abi_check.py

@@ -148,7 +148,8 @@ class AbiChecker(object):
         my_environment = os.environ.copy()
         my_environment["CFLAGS"] = "-g -Og"
         my_environment["SHARED"] = "1"
-        my_environment["USE_CRYPTO_SUBMODULE"] = "1"
+        if os.path.exists(os.path.join(git_worktree_path, "crypto")):
+            my_environment["USE_CRYPTO_SUBMODULE"] = "1"
         make_output = subprocess.check_output(
             [self.make_command, "lib"],
             env=my_environment,