openvpn: fix segfaults since we upgraded to 2.3.11+

After some upstream refactoring, a #include is missing (at least up to 2.3.14),
but still pulled implicitely when openssl is built with engines. This commit
fixes the configure step, so that HAVE_OPENSSL_ENGINE is true as expected.

More on https://community.openvpn.net/openvpn/ticket/792

component/openvpn/buildout.cfg

@@ -19,9 +19,9 @@ environment =
   PATH=${xz-utils:location}/bin:%(PATH)s
   LZO_LIBS=-L${lzo:location}/lib -llzo2
   LZO_CFLAGS=-I${lzo:location}/include
-  OPENSSL_SSL_LIBS="-L${openssl:location}/lib -lssl" 
-  OPENSSL_SSL_CFLAGS="-I${openssl:location}/include/" 
-  OPENSSL_CRYPTO_LIBS="-L${openssl:location}/lib -lcrypto" 
-  OPENSSL_CRYPTO_CFLAGS="-I${openssl:location}/include"
+  OPENSSL_SSL_LIBS=-L${openssl:location}/lib -lssl
+  OPENSSL_SSL_CFLAGS=-I${openssl:location}/include
+  OPENSSL_CRYPTO_LIBS=-L${openssl:location}/lib -lcrypto
+  OPENSSL_CRYPTO_CFLAGS=-I${openssl:location}/include
   LDFLAGS =-Wl,-rpath=${lzo:location}/lib -Wl,-rpath=${flex:location}/lib -Wl,-rpath=${openssl:location}/lib
   CPPFLAGS=-I${lzo:location}/include -I${flex:location}/include