Kernel/LibC: Rework userspace syscall interface

Kernel syscall API no longer zeros all unused argument registers and
libc now uses inlined syscall macro internally. This significantly
cleans up generated code for basic syscall wrapper functions.

userspace/programs/DynamicLoader/utils.cpp

@@ -2,6 +2,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <sys/syscall.h>
 #include <unistd.h>
 
 void print(int fd, const char* buffer)