fix warning about multiple definitions of 'clean'

common/common.am

@@ -82,6 +82,6 @@ lintcheck:
 .PHONY: test
 test: lintcheck linkcheck
 
+CLEAN_FILES = $(PDF) build $(HTML)
 clean:
-	rm -f $(PDF)
-	rm -rf build $(HTML)
+	rm -rf $(CLEAN_FILES)

wolfSSL/Makefile

@@ -2,6 +2,7 @@
 .DEFAULT_GOAL := all
 all: pdf html
 
+CLEAN_FILES += api wolfssl
 
 SOURCES = chapter01.md \
 		  chapter02.md \
@@ -95,10 +96,3 @@ pdf-prep: api
 	$(Q)cat build/pdf/group__ASN.md build/pdf/group__Base__Encoding.md build/pdf/group__Compression.md build/pdf/group__Error.md build/pdf/group__IoTSafe.md build/pdf/group__Keys.md build/pdf/group__Logging.md build/pdf/group__Math.md build/pdf/group__Random.md build/pdf/group__Signature.md build/pdf/group__wolfCrypt.md build/pdf/group__DES.md build/pdf/group__AES.md build/pdf/group__ARC4.md build/pdf/group__BLAKE2.md build/pdf/group__Camellia.md build/pdf/group__ChaCha.md build/pdf/group__ChaCha20Poly1305.md build/pdf/group__Crypto.md build/pdf/group__Curve25519.md build/pdf/group__Curve448.md build/pdf/group__DSA.md build/pdf/group__Diffie-Hellman.md build/pdf/group__ECC.md build/pdf/group__ED25519.md build/pdf/group__ED448.md build/pdf/group__PSA.md  build/pdf/group__SipHash.md >> build/pdf/appendix02.md
 	$(Q)cat build/pdf/aes_8h.md build/pdf/arc4_8h.md build/pdf/asn_8h.md build/pdf/asn__public_8h.md build/pdf/blake2_8h.md build/pdf/bn_8h.md build/pdf/camellia_8h.md build/pdf/chacha20__poly1305_8h.md build/pdf/chacha_8h.md build/pdf/cmac_8h.md build/pdf/coding_8h.md build/pdf/compress_8h.md build/pdf/cryptocb_8h.md build/pdf/curve25519_8h.md build/pdf/curve448_8h.md build/pdf/des3_8h.md build/pdf/dh_8h.md build/pdf/doxygen__groups_8h.md build/pdf/doxygen__pages_8h.md build/pdf/dsa_8h.md build/pdf/ecc_8h.md build/pdf/eccsi_8h.md build/pdf/ed25519_8h.md build/pdf/ed448_8h.md build/pdf/error-crypt_8h.md build/pdf/evp_8h.md build/pdf/hash_8h.md build/pdf/hmac_8h.md build/pdf/iotsafe_8h.md build/pdf/logging_8h.md build/pdf/md2_8h.md build/pdf/md4_8h.md build/pdf/md5_8h.md build/pdf/memory_8h.md build/pdf/pem_8h.md build/pdf/pkcs11_8h.md build/pdf/pkcs7_8h.md build/pdf/poly1305_8h.md build/pdf/psa_8h.md build/pdf/pwdbased_8h.md build/pdf/quic_8h.md build/pdf/random_8h.md build/pdf/ripemd_8h.md build/pdf/rsa_8h.md build/pdf/sakke_8h.md build/pdf/sha256_8h.md build/pdf/sha512_8h.md build/pdf/sha_8h.md build/pdf/signature_8h.md build/pdf/siphash_8h.md build/pdf/srp_8h.md build/pdf/ssl_8h.md build/pdf/tfm_8h.md build/pdf/types_8h.md build/pdf/wc__encrypt_8h.md build/pdf/wc__port_8h.md build/pdf/wolfio_8h.md >> build/pdf/appendix03.md
 
-
-clean:
-	rm -f $(PDF)
-	rm -rf build
-	rm -rf $(HTML)
-	rm -rf api
-	rm -rf wolfssl