Trust STM32 gcc versions

Marlin/src/HAL/STM32/HAL.h

 
 extern "C" char* _sbrk(int incr);
 
-#if GCC_VERSION <= 50000
-  #pragma GCC diagnostic push
-  #pragma GCC diagnostic ignored "-Wunused-function"
-#endif
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-function"
 
 static inline int freeMemory() {
   volatile char top;
   return &top - reinterpret_cast<char*>(_sbrk(0));
 }
 
-#if GCC_VERSION <= 50000
-  #pragma GCC diagnostic pop
-#endif
+#pragma GCC diagnostic pop
 
 //
 // ADC

Marlin/src/HAL/STM32F1/HAL.h

 
 void _delay_ms(const int delay);
 
-#if GCC_VERSION <= 50000
-  #pragma GCC diagnostic push
-  #pragma GCC diagnostic ignored "-Wunused-function"
-#endif
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-function"
 
 /*
 extern "C" {
   return &top - _sbrk(0);
 }
 
-#if GCC_VERSION <= 50000
-  #pragma GCC diagnostic pop
-#endif
+#pragma GCC diagnostic pop
 
 //
 // ADC