Do not use @ which is not always available. Use "" instead (which is not perfect but should be better).

mcs/tools/mkbundle/mkbundle.cs

@@ -176,7 +176,7 @@ class MakeBundle {
 				".globl {0}\n" +
 				"\t.section .rodata\n" +
 				"\t.p2align 5\n" +
-				"\t.type {0}, @object\n" +
+				"\t.type {0}, \"object\"\n" +
 				"\t.size {0}, {1}\n" +
 				"{0}:\n",
 				name, size);