Remove 'ap3_post_variant.h'

Functionality is moved to individual modules, particularly because the include order was incorrect causing redefinitions of symbols like 'SS' by the variant files

Author: oclyke

cores/arduino/ard_sup/Arduino.h

@@ -83,6 +83,4 @@ extern "C"
 
 #include "variant.h"
 
-#include "ap3_post_variant.h"
-
 #endif // _ARDUINO_H_

cores/arduino/ard_sup/ap3_post_variant.h

@@ -23,6 +23,20 @@
 #include <Arduino.h>
 #include "ap3_iomaster.h"
 
+// Give a warning if the variant did not define these symbols:
+#ifndef SS
+#warning "variant has no definition for pin number 'SS'"
+#endif  // SS
+#ifndef MOSI
+#warning "variant has no definition for pin number 'MOSI'"
+#endif  // MOSI
+#ifndef MISO
+#warning "variant has no definition for pin number 'MISO'"
+#endif  // MISO
+#ifndef CLK
+#warning "variant has no definition for pin number 'CLK'"
+#endif  // CLK
+
 // SPI_HAS_TRANSACTION means SPI has
 //   - beginTransaction()
 //   - endTransaction()