gettid syscall, fix issues with vmm and mmap syscall

src/sys/syscalls/gettid.c

@@ -0,0 +1,9 @@
+#include <kernel/syscalls.h>
+#include <arch/cls.h>
+
+syscallret syscall_gettid(){
+	syscallret retv;
+	retv.errno = 0;
+	retv.ret = arch_getcls()->thread->tid;
+	return retv;
+}