Try to make a NOTREACHED definition suitable for win8.

Try to make a NOTREACHED definition suitable for win8.

See http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_gn_rel/builds/5674

Testing this is a two-step process: land CL to pdfium, then try DEPS roll
in chromium against this version on the win8 trybots.

TBR=thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/b0115665b0f33971f1b7077740d51e155583cec0

[Tom Sepez, 2015-03-23 16:34:04]

Committed patchset #1 (id:1) manually as
b0115665b0f33971f1b7077740d51e155583cec0 (presubmit successful).

[Lei Zhang, 2015-03-23 18:54:34]

Have you tried this on Windows to make sure assert(false) doesn't trigger the
same warning? Would you like me to if you haven't?

For the record, since logs don't stay around forever, the error was:

e:\b\build\slave\win_gn\build\src\third_party\pdfium\samples\image_diff_png.cc(246)
: error C2220: warning treated as error - no 'object' file generated
e:\b\build\slave\win_gn\build\src\third_party\pdfium\samples\image_diff_png.cc(246)
: warning C4702: unreachable code
e:\b\build\slave\win_gn\build\src\third_party\pdfium\samples\image_diff_png.cc(574)
: warning C4702: unreachable code

and the build config is:

gn gen //out/Release --args=symbol_level=1 is_debug=false target_cpu="x86"
host_cpu="x86"

[Tom Sepez, 2015-03-23 18:56:54]

Lei, by all means, try.  More data is better.

I got a green result on
http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_gn_...

which was borked before, so I'm feeling better.

[Lei Zhang, 2015-03-23 20:40:30]

This does fix the warning, so lgtm.

BTW commit 7b4c0028550c32b0b773368ff4bbcc1d1adcd928 also turned off this
warning.