Added attribute tests from compiler-polyfill

from https://github.com/ARMmbed/compiler-polyfill/tree/master/test/attributes

hal/TESTS/api/toolchain/attributes.c

@@ -0,0 +1,61 @@
+#include "toolchain.h"
+
+#include <stdio.h>
+#include <stdint.h>
+
+
+struct TestAttrPackedStruct {
+    char a;
+    int x;
+} PACKED;
+
+int testPacked() {
+    int failed = 0;
+
+    if (sizeof(struct TestAttrPackedStruct) != sizeof(int) + sizeof(char)) {
+        failed++;
+    }
+
+    return failed;
+}
+
+
+int testUnused1(UNUSED int arg) {
+    return 0;
+}
+
+int testUnused() {
+    return testUnused1(0);
+}
+
+
+DEPRECATED("this message should not be displayed")
+void testDeprecatedUnused(); 
+void testDeprecatedUnused() { }
+
+DEPRECATED("this message should be displayed")
+int testDeprecatedUsed();
+int testDeprecatedUsed() {
+    return 0;
+}
+
+int testDeprecated() {
+    return testDeprecatedUsed();
+}
+
+
+int testWeak1();
+int testWeak2();
+
+WEAK int testWeak1() {
+    return 1;
+}
+
+int testWeak2() {
+    return 0;
+}
+
+int testWeak() {
+    return testWeak1() | testWeak2();
+}
+

hal/TESTS/api/toolchain/main.cpp

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdint.h>
+
+#include "toolchain.h"
+#include "test_env.h"
+#include "unity.h"
+#include "utest.h"
+
+using namespace utest::v1;
+
+
+// Test functions declared as C functions to avoid issues with name mangling
+extern "C" {
+    int testPacked();
+    int testUnused();
+    int testDeprecated();
+    int testWeak();
+}
+
+
+// Test wrapper and test cases for utest
+template <int (*F)()>
+void test_wrapper() {
+    TEST_ASSERT_UNLESS(F());
+}
+
+status_t test_setup(const size_t number_of_cases) {
+    GREENTEA_SETUP(40, "default_auto");
+    return verbose_test_setup_handler(number_of_cases);
+}
+
+Case cases[] = {
+    Case("Testing PACKED attribute",     test_wrapper<testPacked>),
+    Case("Testing UNUSED attribute",     test_wrapper<testUnused>),
+    Case("Testing DEPRECATED attribute", test_wrapper<testDeprecated>),
+    Case("Testing WEAK attribute",       test_wrapper<testWeak>),
+};
+
+Specification specification(test_setup, cases);
+
+int main() {
+    return !Harness::run(specification);
+}

hal/TESTS/api/toolchain/weak.c

@@ -0,0 +1,10 @@
+#include "toolchain.h"
+
+int testWeak1() {
+    return 0;
+}
+
+WEAK int testWeak2() {
+    return 1;
+}
+