Add initial libfuzzers for fm2js transpiling and XML parsing.

Add initial libfuzzers for fm2js transpiling and XML parsing.

GN source_sets are added so that the fuzzers can be built from
//testing/libfuzzer in a Chromium checkout.

GYP targets are also added to make sure these always build properly on
our waterfall. These don't actually build the proper libfuzzers, but
build the target fuzz function with a driver main() since the actual
build process is quite complicated.

R=tsepez@chromium.org, thestig@chromium.org
BUG=587126
Committed: https://pdfium.googlesource.com/pdfium/+/e67d21825c9fd4b805b9bea211e09225f3c2a85d

[Oliver Chang, 2016-02-16 19:05:06]

ptal

[Tom Sepez, 2016-02-16 19:24:02]

lgtm

[Oliver Chang, 2016-02-16 19:41:30]

(made a trivial change in ps#3 to disable building on Windows, which is
unsupported)

[Oliver Chang, 2016-02-16 19:42:09]

Description was changed from

==========
Add initial libfuzzers for fm2js transpiling and XML parsing.

GN source_sets are added so that the fuzzers can be built from
//testing/libfuzzer in a Chromium checkout.

GYP targets are also added to make sure these always build properly on
our waterfall. These don't actually build the proper libfuzzers, but
build the target fuzz function with a driver main() since the actual
build process is quite complicated.

R=tsepez@chromium.org,thestig@chromium.org
BUG=587126
==========

to

==========
Add initial libfuzzers for fm2js transpiling and XML parsing.

GN source_sets are added so that the fuzzers can be built from
//testing/libfuzzer in a Chromium checkout.

GYP targets are also added to make sure these always build properly on
our waterfall. These don't actually build the proper libfuzzers, but
build the target fuzz function with a driver main() since the actual
build process is quite complicated.

R=tsepez@chromium.org, thestig@chromium.org
BUG=587126

Committed:
https://pdfium.googlesource.com/pdfium/+/e67d21825c9fd4b805b9bea211e09225f3c2...
==========

[Oliver Chang, 2016-02-16 19:42:10]

Committed patchset #3 (id:40001) manually as
e67d21825c9fd4b805b9bea211e09225f3c2a85d (presubmit successful).