misc: Merge branch v21.0.0.0 into develop

This incorporates the last of the v21.0 staging branch changes into the
develop branch.

Change-Id: I89349ac5c52fd454eb87d6199ea5ccde0d50dda3

SConstruct

@@ -322,12 +322,6 @@ if main['GCC'] or main['CLANG']:
     if GetOption('gold_linker'):
         main.Append(LINKFLAGS='-fuse-ld=gold')
 
-    # Treat warnings as errors but white list some warnings that we
-    # want to allow (e.g., deprecation warnings).
-    main.Append(CCFLAGS=['-Werror',
-                         '-Wno-error=deprecated-declarations',
-                         '-Wno-error=deprecated',
-                        ])
 else:
     error('\n'.join((
           "Don't know what compiler options to use for your compiler.",