[stdlib] Merged Glibc code to Platform directory.

Author: rintaro

stdlib/public/CMakeLists.txt

@@ -31,12 +31,11 @@ if(SWIFT_BUILD_STDLIB)
   add_subdirectory(stubs)
   add_subdirectory(core)
   add_subdirectory(SwiftOnoneSupport)
-  add_subdirectory(Glibc)
+  add_subdirectory(Platform)
 endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   if(SWIFT_BUILD_SDK_OVERLAY)
-    add_subdirectory(Platform)
     add_subdirectory(SDK)
   endif()
 endif()