Initialize uvisor-lib

uvisor-lib has an init function that must be called before the RTOS kernel
is initialized. Call uvisor_lib_init from software_init_hook to accomplish
this.

Author: Patater

hal/common/retarget.cpp

@@ -413,13 +413,26 @@ extern "C" WEAK void __cxa_pure_virtual(void) {
 #endif
 
 #if defined(TOOLCHAIN_GCC)
+#ifdef   FEATURE_UVISOR
+#include "uvisor-lib/uvisor-lib.h"
+#endif/* FEATURE_UVISOR */
+
 extern "C" WEAK void software_init_hook_rtos(void)
 {
     // Do nothing by default.
 }
 
 extern "C" void software_init_hook(void)
 {
+#ifdef   FEATURE_UVISOR
+    int return_code;
+
+    return_code = uvisor_lib_init();
+    if (return_code) {
+        mbed_die();
+    }
+#endif/* FEATURE_UVISOR */
+
     software_init_hook_rtos();
 }
 #endif