Add macros to assert status and use it

These macros are to be used to check the status from calls that are flagged
by Coverity as 'Unchecked return value'.

Fix file assert.h

cpukit/include/rtems/score/assert.h

@@ -98,6 +98,36 @@ extern "C" {
   #define _Assert( _e ) ( ( void ) 0 )
 #endif
 
+/**
+ * @brief Assert if unused return value is equal.
+ *
+ * Assert whether @a _var and @a _val are equal and ensure @a _var is
+ * marked as used when not building for debug.
+ *
+ * @param _var The return value to be checked.
+ * @param _val Indicates what @a _var is supposed to be.
+ */
+#define _Assert_Unused_variable_equals(_var,_val) \
+        do { \
+          _Assert((_var) == (_val)); \
+          (void) (_var); \
+        } while (0)
+
+/**
+ * @brief Assert if unused return value is not equal.
+ *
+ * Assert whether @a _var and @a _val are not equal and ensure @a _var
+ * is marked as used when not building for debug.
+ *
+ * @param _var The return value to be checked.
+ * @param _val Indicates what @a _var is not supposed to be.
+ */
+#define _Assert_Unused_variable_unequal(_var,_val) \
+         do { \
+          _Assert((_var) != (_val)); \
+           (void) (_var); \
+        } while (0)
+
 /**
  * @brief Returns true if thread dispatching is allowed.
  *