Replace automatic SSL certificate generation with generate_cert bui…

…ld target

Sming/Components/ssl/README.rst

@@ -11,6 +11,20 @@ Sming supports multiple SSL implementations, currently with adapters for:
 If you want to use SSL then take a look at the :sample:`Basic_Ssl` sample for creating SSL clients,
 and :sample:`HttpServer_ConfigNetwork` for SSL servers.
 
+Certificates
+------------
+
+If you need an X509 certificate and private key::
+
+   make generate-cert
+
+This will use openssl to generate binary certificate and key information in ``out/ssl``
+and create ``include/ssl/cert.h`` and ``include/ssl/private_key.h``.
+See :sample:`MqttClient_Hello` and :sample:`SmtpClient` for how these are used in code.
+
+An alternative to generating header files is to use the binary certificate files directly.
+See :sample:`Basic_AWS` for an example of this approach.
+
 
 Configuration Variables
 -----------------------

Sming/Components/ssl/component.mk

@@ -41,12 +41,14 @@ ifeq ($(ENABLE_SSL),0)
 else
 	$(info Using $(ENABLE_SSL) SSL implementation)
 
-# Application
-CUSTOM_TARGETS			+= include/ssl/private_key.h
+##@Tools
+
+.PHONY: generate_cert
+generate_cert: include/ssl/private_key.h ##Generate X509 certificate and private key files in include/ssl
 
 SSL_TOOLS_PATH			:= $(COMPONENT_PATH)/Tools
 SSL_INCLUDE_DIR			:= $(PROJECT_DIR)/include/ssl
-OUT_SSL                         := out/ssl/
+OUT_SSL                 := out/ssl/
 SSL_CERT_DIR			:= $(OUT_SSL)/cert
 
 include/ssl/private_key.h: