stdlib: Don't explicitly pass requirement machine flags that are on by default

Author: slavapestov

stdlib/cmake/modules/SwiftSource.cmake

@@ -465,12 +465,6 @@ function(_compile_swift_files
     endif()
   endif()
 
-  # The standard library and overlays are built with the Requirement Machine enabled.
-  if(SWIFTFILE_IS_STDLIB)
-    list(APPEND swift_flags "-Xfrontend" "-requirement-machine-protocol-signatures=verify")
-    list(APPEND swift_flags "-Xfrontend" "-requirement-machine-abstract-signatures=verify")
-  endif()
-
   # The standard library and overlays are built resiliently when SWIFT_STDLIB_STABLE_ABI=On.
   if(SWIFTFILE_IS_STDLIB AND SWIFT_STDLIB_STABLE_ABI)
     list(APPEND swift_flags "-enable-library-evolution")