mraa: add deinit function for valgrind testing

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa/common.h

@@ -186,6 +186,14 @@ mraa_result_t mraa_init() __attribute__((constructor));
 mraa_result_t mraa_init();
 #endif
 
+/**
+ * De-Initilise MRAA
+ *
+ * This is not a strict requirement but useful to test memory leaks and for
+ * people who like super clean code.
+ */
+void mraa_deinit();
+
 /**
  * Checks if a pin is able to use the passed in mode.
  *

examples/hellomraa.c

@@ -30,6 +30,7 @@ int
 main(int argc, char **argv)
 {
     fprintf(stdout, "hello mraa\n Version: %s\n", mraa_get_version());
+    mraa_deinit();
     return 0;
 }
 //! [Interesting]

src/mraa.c

@@ -98,6 +98,13 @@ mraa_init()
     return MRAA_SUCCESS;
 }
 
+void
+mraa_deinit()
+{
+    free(plat->pins);
+    free(plat);
+}
+
 int
 mraa_set_priority(const unsigned int priority)
 {