Implement argument_ptr () syscall for handling process arguments

libmsl/proc/proc.c

@@ -5,13 +5,15 @@
 #include <stddef.h>
 #include <stdint.h>
 
-int process_spawn (process_func_t func) {
+int process_spawn (process_func_t func, void* argument_ptr) {
   void* stack = malloc (PROC_STACK_SIZE);
   if (stack == NULL)
     return -ST_OOM_ERROR;
 
   uintptr_t top = (uintptr_t)stack + PROC_STACK_SIZE;
-  return clone (top, func);
+  return clone (top, func, argument_ptr);
 }
 
 int process_quit (void) { return quit (); }
+
+void* process_argument (void) { return argument_ptr (); }