Restore headers for low-level symmetric primitives

This restores the now-private headers as public again after open-quantum-safe#1667,
exposing the API to select alternative implementation through
callbacks, e.g., OQS_AES_set_callbacks.  Note the other functions in
those headers are still not exposed as they are declared without
OQS_API.

Signed-off-by: Daiki Ueno <dueno@redhat.com>

CMakeLists.txt

@@ -150,17 +150,17 @@ if(${OQS_USE_OPENSSL})
 endif()
 
 set(PUBLIC_HEADERS ${PROJECT_SOURCE_DIR}/src/oqs.h
+                   ${PROJECT_SOURCE_DIR}/src/common/aes/aes.h
+		   ${PROJECT_SOURCE_DIR}/src/common/sha2/sha2.h
+		   ${PROJECT_SOURCE_DIR}/src/common/sha3/sha3.h
+		   ${PROJECT_SOURCE_DIR}/src/common/sha3/sha3x4.h
                    ${PROJECT_SOURCE_DIR}/src/common/common.h
                    ${PROJECT_SOURCE_DIR}/src/common/rand/rand.h
                    ${PROJECT_SOURCE_DIR}/src/kem/kem.h
                    ${PROJECT_SOURCE_DIR}/src/sig/sig.h
                    ${PROJECT_SOURCE_DIR}/src/sig_stfl/sig_stfl.h)
 
-set(INTERNAL_HEADERS ${PROJECT_SOURCE_DIR}/src/common/aes/aes.h
-                     ${PROJECT_SOURCE_DIR}/src/common/rand/rand_nist.h
-                     ${PROJECT_SOURCE_DIR}/src/common/sha2/sha2.h
-                     ${PROJECT_SOURCE_DIR}/src/common/sha3/sha3.h
-                     ${PROJECT_SOURCE_DIR}/src/common/sha3/sha3x4.h)
+set(INTERNAL_HEADERS ${PROJECT_SOURCE_DIR}/src/common/rand/rand_nist.h)
 
 if(${OQS_ENABLE_KEM_BIKE})
     set(PUBLIC_HEADERS ${PUBLIC_HEADERS} ${PROJECT_SOURCE_DIR}/src/kem/bike/kem_bike.h)