Nintendo switch support (#8069)

* Add config section for Nintendo Switch
* Add compiler configuration for Nintendo Switch and it's CPU
* Add specific lib code for Nintendo Switch
* Add GC support for Nintendo Switch
* Update changelog for Nintendo Switch
* Update changelog with more info about fixed paths
* Cleaned up GC memory management a bit
* Relocate docs for Switch
* Rename aarch64NoneElfGcc to nintendoSwitchGCC
* Remove armv8a57
* Fix installer.ini
* Reuse code in linux and amd64
* Add posix defs for nintendo switch
* Add more defined sections for nintendo switch
* Remove old comment
* Add what's not supported for Nintendo Switch docs
* Make nintendoswitch == posix
* Remove DEVKITPRO references from nim.cfg
* Make PR extccomp changes
* Remove Result type alias
* Add separate switch consts file
* Update docs for nintendo switch
* Fix travis errors with undefined consts and add correct wait.h procs

compiler/platform.nim

@@ -22,7 +22,7 @@ type
     osNone, osDos, osWindows, osOs2, osLinux, osMorphos, osSkyos, osSolaris,
     osIrix, osNetbsd, osFreebsd, osOpenbsd, osDragonfly, osAix, osPalmos, osQnx,
     osAmiga, osAtari, osNetware, osMacos, osMacosx, osHaiku, osAndroid, osVxworks
-    osGenode, osJS, osNimVM, osStandalone
+    osGenode, osJS, osNimVM, osStandalone, osNintendoSwitch
 
 type
   TInfoOSProp* = enum
@@ -168,7 +168,12 @@ const
      (name: "Standalone", parDir: "..", dllFrmt: "lib$1.so", altDirSep: "/",
       objExt: ".o", newLine: "\x0A", pathSep: ":", dirSep: "/",
       scriptExt: ".sh", curDir: ".", exeExt: "", extSep: ".",
-      props: {})]
+      props: {}),
+     (name: "NintendoSwitch", parDir: "..", dllFrmt: "lib$1.so", altDirSep: "/",
+      objExt: ".o", newLine: "\x0A", pathSep: ":", dirSep: "/",
+      scriptExt: ".sh", curDir: ".", exeExt: ".elf", extSep: ".",
+      props: {ospNeedsPIC, ospPosix}),
+     ]
 
 type
   TSystemCPU* = enum # Also add CPU for in initialization section and