Review corrections

-Guard additional static variables with AES_ONLY_ENCRYPT
-Update config.h description about memory savings
-Update test: fix typo in all.sh and adjust compiler flags
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 90dfea5..b820115 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -1278,9 +1278,9 @@
 component_test_aes_only_encrypt () {
     msg "build: default config with MBEDTLS_AES_ONLY_ENCRYPT enabled"
     scripts/config.pl set MBEDTLS_AES_ONLY_ENCRYPT
-    make CC=gcc CFLAGS='-Werror -Wall -Wextra'
+    make CC=gcc CFLAGS='-Werror -O1'
 
-    msg "test: AES_ONLY_128_BIT_KEY_LENGTH"
+    msg "test: AES_ONLY_ENCRYPT"
     make test
 }