re2: rename DISALLOW_EVIL_CONSTRUCTORS to DISALLOW_COPY_AND_ASSIGN

Political correctness for the win.

Change-Id: I3b3e5f7a565cb115c667386da7a94b5abcc0093d
Reviewed-on: https://code-review.googlesource.com/1590
Reviewed-by: Russ Cox <rsc@swtch.com>
fix a -Wsign-compare warning

https://code-review.googlesource.com/#/c/1272/ turned on -Wsign-compare, but
missed one place where the warning fires.

Change-Id: I0739d935b96da093a7151784274fdb7335e7f5cc
Reviewed-on: https://code-review.googlesource.com/1550
Reviewed-by: Russ Cox <rsc@swtch.com>
re2: import various changes from Google's copy

Change-Id: I63bd284d742da393713dfdd0164d2ff38fd44920
Reviewed-on: https://code-review.googlesource.com/1592
Reviewed-by: Russ Cox <rsc@swtch.com>
re2: three minor bug fixes

Found during testing inside Google.

Change-Id: I93f824fd828b93b214c62b69b93d58f841b83bf1
Reviewed-on: https://code-review.googlesource.com/1593
Reviewed-by: Russ Cox <rsc@swtch.com>
Compile re with MSVC 2013