expose source alloc fully

src/mid/source_alloc.rs

@@ -43,6 +43,13 @@ impl SourceAlloc {
             )
         })
     }
+
+    /// returns the underlying source allocator
+    ///
+    /// the source allocator has more functions which may be useful
+    pub fn get_underlying_alloc(&self) -> &'static IMemAlloc {
+        self.0.wait().get()
+    }
 }
 
 unsafe impl GlobalAlloc for SourceAlloc {