Num-to-string functions for DEBUG_LEVELING_FEATURE

Marlin/src/core/utility.h

   FORCE_INLINE bool is_bitmap_set(uint16_t bits[16], const uint8_t x, const uint8_t y) { return TEST(bits[y], x); }
 #endif
 
-#if ENABLED(ULTRA_LCD)
+#if ENABLED(ULTRA_LCD) || ENABLED(DEBUG_LEVELING_FEATURE)
 
   // Convert uint8_t to string with 123 format
   char* i8tostr3(const uint8_t x);

Marlin/src/feature/bedlevel/ubl/ubl.h

 
 // External references
 
-char *ftostr43sign(const float&, char);
-
 extern uint8_t ubl_cnt;
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////////