Update dependencies.

Replace TEST_CASE with TEST_SUITE. (google#29)

Add shared library mode to Travis CI. (google#24)

CMake: fix include install path. (google#12)

Fix SSE4.2 arch flag for MSVC in CMake config. (#8)

The old flag was a copy-paste error. We only use /arch:NOTYET for the
ARM64-specific hardware accelerated implementation, because Visual Studio
does not yet have an equivalent to -march=armv8-a+crc+crypto.

Gate ARM64-accelerated impl on hwcap() having the HWCAP_PMULL flag. (#6)

The hardware-accelerated CRC32C implementation that takes advantage of
ARM64 instructions is currently runtime-gated on hwcap() returning a
value that has the HWCAP_CRC32 flag set. This covers the
__crc32c{b,h,w,d} intrinsics, but does not cover the vmull_p64 call. The
later should be gated on the presence of the HWCAP_PMULL flag.

This is a speculative fix for Chrome crashes observed at the first
vmull_64 callsite on MSM8916-based boards.

More conservative check for <string_view> availability. (#4)

has_include(<string_view>) does not imply that the header can be
included and will work. The assumption fails on MSVC and libc++ [1, 2].
Conversely, checking that __cplusplus > 201402L is not sufficient on its
own either, as the toolchain on Mac OS 10.12 passes that check but does
not contain a <string_view> header.

[1] https://crbug.com/759349
[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79433

Fix MSVC warnings in crc32c_unittest.cc. (#3)

This also modifies the CMake configuration, so relevant build targets
will be compiled with /WX (warnings-as-errors) on MSVC. This should help
us catch similar errors in CI in the future.

Fixed copyright year for imported code.