Allow omitting code and ISR for specific UARTs

This is controlled by the variant defining `SKIP_UARTx` and frees up the
corresponding ISR to be used directly.

Author: matthijskooijman

libraries/SrcWrapper/src/stm32/uart.c

@@ -58,6 +58,37 @@ extern "C" {
 #define DEBUG_UART_BAUDRATE 9600
 #endif
 
+#if defined(SKIP_UART1)
+#undef USART1_BASE
+#endif
+#if defined(SKIP_UART2)
+#undef USART2_BASE
+#endif
+#if defined(SKIP_UART3)
+#undef USART3_BASE
+#endif
+#if defined(SKIP_UART4)
+#undef USART4_BASE
+#endif
+#if defined(SKIP_UART5)
+#undef USART5_BASE
+#endif
+#if defined(SKIP_UART6)
+#undef USART6_BASE
+#endif
+#if defined(SKIP_UART7)
+#undef USART7_BASE
+#endif
+#if defined(SKIP_UART8)
+#undef USART8_BASE
+#endif
+#if defined(SKIP_UART9)
+#undef USART9_BASE
+#endif
+#if defined(SKIP_UART10)
+#undef USART10_BASE
+#endif
+
 /* @brief uart caracteristics */
 typedef enum {
 #if defined(USART1_BASE)