Fix unreferenced errors with mingw compiler and unit tests

tests/test_common/matrix.c

@@ -58,3 +58,6 @@ void release_key(uint8_t col, uint8_t row) {
 void clear_all_keys(void) {
     memset(matrix, 0, sizeof(matrix));
 }
+
+void led_set(uint8_t usb_led) {
+}

tests/test_common/test_fixture.cpp

@@ -44,8 +44,8 @@ void TestFixture::run_one_scan_loop() {
     advance_time(1);
 }
 
-void TestFixture::idle_for(uint time) {
-    for (uint i=0; i<time; i++) {
+void TestFixture::idle_for(unsigned time) {
+    for (unsigned i=0; i<time; i++) {
         run_one_scan_loop();
     }
 }

tests/test_common/test_fixture.hpp

@@ -26,5 +26,5 @@ public:
     static void TearDownTestCase();
 
     void run_one_scan_loop();
-    void idle_for(uint ms);
+    void idle_for(unsigned ms);
 };