PicoSDK: Build STDIO components only if requested

Author: maxgerhardt

builder/frameworks/picosdk.py

@@ -542,16 +542,22 @@ def configure_printf_impl():
     ("pico_runtime_init", "+<*>"),
     ("pico_runtime", "+<*>"),
     ("pico_status_led", "+<*>"),
-    ("pico_stdio_rtt", "+<*>"),
-    ("pico_stdio_semihosting", "+<*>"),
-    ("pico_stdio_uart", "+<*>"),
-    ("pico_stdio_usb", "+<*>"),
     ("pico_stdio", "+<*>"),
     ("pico_stdlib", "+<*>"),
     ("pico_standard_binary_info", "+<*>"),
     ("pico_unique_id", "+<*>"),
 ]
 
+# multiple stdio implementations can be on at the same time!
+if "LIB_PICO_STDIO_USB" in flags:
+    default_common_rp2_components.append(("pico_stdio_usb", "+<*>"))
+if "LIB_PICO_STDIO_UART" in flags:
+    default_common_rp2_components.append(("pico_stdio_uart", "+<*>"))
+if "LIB_PICO_STDIO_SEMIHOSTING" in flags:
+    default_common_rp2_components.append(("pico_stdio_semihosting", "+<*>"))
+if "LIB_PICO_STDIO_RTT" in flags:
+    default_common_rp2_components.append(("pico_stdio_rtt", "+<*>"))
+
 if is_rp2350:
     default_common_rp2_components.extend(
         [