Add specific lib code for Nintendo Switch

lib/pure/os.nim

@@ -819,7 +819,8 @@ iterator walkDir*(dir: string; relative=false): tuple[kind: PathComponent, path:
               y = dir / y
             var k = pcFile
 
-            when defined(linux) or defined(macosx) or defined(bsd) or defined(genode):
+            when defined(linux) or defined(macosx) or
+                 defined(bsd) or defined(genode) or defined(nintendoswitch):
               if x.d_type != DT_UNKNOWN:
                 if x.d_type == DT_DIR: k = pcDir
                 if x.d_type == DT_LNK:
@@ -1285,7 +1286,7 @@ elif defined(windows):
 
 elif not defined(createNimRtl) and
   not(defined(posix) and appType == "lib") and
-  not defined(genode):
+  not defined(genode) and not defined(nintendoswitch):
   # On Posix, there is no portable way to get the command line from a DLL.
   var
     cmdCount {.importc: "cmdCount".}: cint
@@ -1439,7 +1440,7 @@ proc getAppFilename*(): string {.rtl, extern: "nos$1", tags: [ReadIOEffect].} =
       result = getApplAux("/proc/self/exe")
     elif defined(solaris):
       result = getApplAux("/proc/" & $getpid() & "/path/a.out")
-    elif defined(genode):
+    elif defined(genode) or defined(nintendoswitch):
       raiseOSError(OSErrorCode(-1), "POSIX command line not supported")
     elif defined(freebsd) or defined(dragonfly):
       result = getApplFreebsd()

lib/pure/selectors.nim

@@ -312,6 +312,8 @@ else:
     include ioselects/ioselectors_poll # need to replace it with event ports
   elif defined(genode):
     include ioselects/ioselectors_select # TODO: use the native VFS layer
+  elif defined(nintendoswitch):
+    include ioselects/ioselectors_select
   else:
     include ioselects/ioselectors_poll