Merge "Make FlexLexer buildable for native_bridge" am: 6d1df66700 am: e8be11c9e7 am: 3b0bf4a3e2 am: 5c0fb165b4 am: c7f5aeeb01

Original change: https://android-review.googlesource.com/c/platform/external/eigen/+/1308019

Change-Id: Id8f702b7d38f2a2c73f87bb126152a48cc508e28