test: update keys/Makefile to clean and build all

Currently when running make clean, followed by make not all certificates
get genenerated. In addition there are also the following error messages
related to the startdate in agent8-cert.pem, and agent9-cert.pem:
start date is invalid, it should be YYMMDDHHMMSSZ

After this commit it is possible to perform the following commands:
$ make clean
$ make
$ make test

PR-URL: #19975
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/fixtures/keys/Makefile

@@ -1,4 +1,4 @@
-all: agent1-cert.pem agent2-cert.pem agent3-cert.pem agent4-cert.pem agent5-cert.pem ca2-crl.pem ec-cert.pem dh512.pem dh1024.pem dh2048.pem dsa1025.pem dsa_private_1025.pem dsa_public_1025.pem rsa_private_1024.pem rsa_private_2048.pem rsa_private_4096.pem rsa_public_1024.pem rsa_public_2048.pem rsa_public_4096.pem
+all: agent1-cert.pem agent1-pfx.pem agent2-cert.pem agent3-cert.pem agent4-cert.pem agent5-cert.pem agent6-cert.pem agent7-cert.pem agent8-cert.pem agent9-cert.pem ca1-cert.pem ca2-crl.pem ca3-cert.pem ec-cert.pem dh512.pem dh1024.pem dh2048.pem dsa1025.pem dsa_private_1025.pem dsa_public_1025.pem rsa_private_1024.pem rsa_private_2048.pem rsa_private_4096.pem rsa_public_1024.pem rsa_public_2048.pem rsa_public_4096.pem
 
 
 #
@@ -280,7 +280,7 @@ agent8-csr.pem: agent8.cnf agent8-key.pem
 	openssl req -new -config agent8.cnf -key agent8-key.pem \
 	-out agent8-csr.pem
 
-agent8-cert.pem: agent8-csr.pem
+agent8-cert.pem: agent8-csr.pem fake-startcom-root-cert.pem fake-startcom-root-key.pem
 	openssl ca \
 		-config fake-startcom-root.cnf \
 		-keyfile fake-startcom-root-key.pem \
@@ -289,7 +289,7 @@ agent8-cert.pem: agent8-csr.pem
 		-days 9999 \
 		-passin "pass:password" \
 		-in agent8-csr.pem \
-		-startdate 20161020235959Z \
+		-startdate 161020235959Z \
 		-notext -out agent8-cert.pem
 
 
@@ -319,7 +319,7 @@ agent9-cert.pem: agent9-csr.pem
 		-days 9999 \
 		-passin "pass:password" \
 		-in agent9-csr.pem \
-		-startdate 20161021000001Z \
+		-startdate 161021000001Z \
 		-notext -out agent9-cert.pem
 
 ec-key.pem:
@@ -380,7 +380,8 @@ rsa_public_4096.pem: rsa_private_4096.pem
 	openssl rsa -in rsa_private_4096.pem -out rsa_public_4096.pem
 
 clean:
-	rm -f *.pem *.srl ca2-database.txt ca2-serial
+	rm -f *.pem *.srl ca2-database.txt ca2-serial fake-startcom-root-serial
+	@> fake-startcom-root-database.txt
 
 test: agent1-verify agent2-verify agent3-verify agent4-verify agent5-verify