WebRTC: Promote Linux 32-bit bots to main waterfall again.

masters/master.client.webrtc/slaves.cfg

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 slaves = [
   # Linux 64-bit.
   {
     'master': 'WebRTC',
     'os': 'linux',
     'version': 'trusty',
     'bits': '64',
     'builder': [
       'Android32 Builder',
       'Android32 Builder (dbg)',
       'Android32 Builder x86',
       'Android32 Builder x86 (dbg)',
       'Android32 Builder MIPS (dbg)',
       'Android32 Clang (dbg)',
       'Android64 Builder',
       'Android64 Builder (dbg)',
       'Android64 Builder x64 (dbg)',
       'Android32 GYP',
       'Android32 GYP (dbg)',
       'Linux32 ARM',
+      'Linux32 Debug',
+      'Linux32 Release',
       'Linux64 Debug',
       'Linux64 Release',
       'Linux64 Debug (GYP)',
       'Linux64 Release (GYP)',
       'Linux64 Release (Libfuzzer)',
       'Linux Asan',
       'Linux MSan',
       'Linux Tsan v2',
       'Linux UBSan',
       'Linux UBSan vptr',
@@ skipping 161 matching lines @@
     'master': 'WebRTC',
     'os': 'win',
     'version': 'win7',
     'bits': '64',
     'builder': [
       'Win32 Release [large tests]',
     ],
     'hostname': 'build20-b3',
   }
 ]