cleanup: namespace Montauk (capital M) => montauk::abi

programs/include/montauk/heap.h

@@ -46,7 +46,7 @@ namespace heap_detail {
 
     static inline void heap_lock_acquire() {
         while (__atomic_exchange_n(&g_heap_lock, 1, __ATOMIC_ACQUIRE) != 0) {
-            syscall0(Montauk::SYS_YIELD);
+            syscall0(montauk::abi::SYS_YIELD);
         }
     }
     static inline void heap_lock_release() {