Fix printf escape errors in shell scripts

Fix `printf "$foo"` which treats the value of `foo` as a printf format
rather than a string.

I used the following command to find potentially problematic lines:
```
git ls-files '*.sh' | xargs egrep 'printf +("?[^"]*|[^ ]*)\$'
```
The remaining ones are false positives for this regexp.

The errors only had minor consequences: the output of `ssl-opt.sh`
contained lines like
```
Renegotiation: gnutls server strict, client-initiated .................. ./tests/ssl-opt.sh: 741: printf: %S: invalid directive
PASS
```
and in case of failure the GnuTLS command containing a substring like
`--priority=NORMAL:%SAFE_RENEGOTIATION` was not included in the log
file. With the current tests, there was no risk of a test failure
going undetected.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/context-info.sh b/tests/context-info.sh
index 150584b..cc5d6ea 100755
--- a/tests/context-info.sh
+++ b/tests/context-info.sh
@@ -433,10 +433,11 @@
 
 # End of tests
 
+echo
 if [ $T_FAILED -eq 0 ]; then
-    printf "\nPASSED ( $T_COUNT tests )\n"
+    echo "PASSED ( $T_COUNT tests )"
 else
-    printf "\nFAILED ( $T_FAILED / $T_COUNT tests )\n"
+    echo "FAILED ( $T_FAILED / $T_COUNT tests )"
 fi
 
 exit $T_FAILED