vm: add RT_SAFEPOINT relocation type

vm/code_blocks.cpp

@@ -272,6 +272,9 @@ void factor_vm::store_external_address(instruction_operand op)
 	case RT_INLINE_CACHE_MISS:
 		op.store_value((cell)&factor::inline_cache_miss);
 		break;
+	case RT_SAFEPOINT:
+		op.store_value((cell)code->safepoint_page);
+		break;
 	default:
 		critical_error("Bad rel type in store_external_address()",op.rel_type());
 		break;

vm/instruction_operands.hpp

@@ -34,7 +34,9 @@ enum relocation_type {
 	RT_DLSYM_TOC,
 	/* address of inline_cache_miss function. This is a separate
 	relocation to reduce compile time and size for PICs. */
-	RT_INLINE_CACHE_MISS
+	RT_INLINE_CACHE_MISS,
+	/* address of safepoint page in code heap */
+	RT_SAFEPOINT
 };
 
 enum relocation_class {