stage1: add missing math.h includes

src/codegen.cpp

@@ -25,6 +25,7 @@
 
 #include <stdio.h>
 #include <errno.h>
+#include <math.h>
 
 enum ResumeId {
     ResumeIdManual,

src/ir.cpp

@@ -19,6 +19,7 @@
 #include "all_types.hpp"
 
 #include <errno.h>
+#include <math.h>
 
 struct IrBuilderSrc {
     CodeGen *codegen;