refactor, libc made optional

Common/mat.h

@@ -21,7 +21,7 @@
 #include "vec.h"
 #include <stdint.h>
 
-typedef union {
+typedef struct {
   com_def_alignedas(64) com_def_vector(com_fix_t, a, 4 * 4);
 } com_mat_t;
 
@@ -130,17 +130,17 @@ static inline com_mat_t com_mat_look_at(com_vec_t pos, com_vec_t up,
 
   com_mat_t result;
 
-  result.a[0] = r.s.x;
-  result.a[1] = u.s.x;
-  result.a[2] = -target.s.x;
+  result.a[0] = r.a[0];
+  result.a[1] = u.a[0];
+  result.a[2] = -target.a[0];
   result.a[3] = 0;
-  result.a[4] = r.s.y;
-  result.a[5] = u.s.y;
-  result.a[6] = -target.s.y;
+  result.a[4] = r.a[1];
+  result.a[5] = u.a[1];
+  result.a[6] = -target.a[1];
   result.a[7] = 0;
-  result.a[8] = r.s.z;
-  result.a[9] = u.s.z;
-  result.a[10] = -target.s.z;
+  result.a[8] = r.a[2];
+  result.a[9] = u.a[2];
+  result.a[10] = -target.a[2];
   result.a[11] = 0;
   result.a[12] = -com_vec_dot(r, pos);
   result.a[13] = -com_vec_dot(u, pos);