Fix another hang bug, fix not printing certain test output

Author: multiplemonomials

targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/serial_api.c

@@ -292,6 +292,15 @@ int serial_getc(serial_t *obj)
             return 'x';
         }
 
+        // Similar to above but with the overflow flag. Without this logic we can hang when receiving
+        // at 921600 baud. Oddly, the overflow flag in RSR does not seem to be reliable, but the overflow
+        // flag in IES seems to be. Not sure why this UART has two overflow flags in the first place, smh...
+        if(bytes_read == 0 && UARTn(obj->serial.uart_control->inst)->IES_b.OERIS)
+        {
+            UARTn(obj->serial.uart_control->inst)->IEC_b.OEIC = 1;
+            return 'x';
+        }
+
     } while (bytes_read == 0);
 
     return (int)rx_c;

tools/python/mbed_os_tools/test/host_tests_conn_proxy/conn_proxy.py

@@ -62,9 +62,11 @@ def append(self, payload: bytes):
                 before = line[:pos]
                 after = line[pos + len(match):]
                 if len(before) > 0:
+                    logger.prn_rxd(before)
                     discarded.append(before)
                 if len(after) > 0:
                     # not a K,V pair part
+                    logger.prn_rxd(after)
                     discarded.append(after)
                 logger.prn_inf("found KV pair in stream: {{%s;%s}}, queued..."% (key, value))
             else: