Update mainDexClasses.rules

To benefit from
- "Adapt mainDexClasses.rules to proguard 4.10"
  60548f3a78778bfb65f30ec2845e3b5d9ee0990a
- "Fix mainDexClasses with obfuscation."
  4f6a857f32dfb9bf17103a2bf94ee0f74cd951ce

Change-Id: If12c31c5edb7d8e7280aa8073fa9bb91b1d91282
1 file changed