Cleanup DEPS, BUILD.gn, make build/ available

[illwieckz]

• Remove BUILD.gn support
• Remove DEPS files
• Ignore /toolchain symbolic link
  This way we can symlink the prebuilt toolchain by Google
  when we need to build with it for investigation purpose.
• Move files from build/ to tools/build/
  Keep the build/ directory available as a build folder.
• Ignore the build/ directory
  It is common practice with CMake to build in build/.

[illwieckz]

Hmm, something broke something:

CC: /home/runner/work/native_client/native_client/sdk/sdk/bin/x86_64-nacl-clang
ASPPCOM: /home/runner/work/native_client/native_client/sdk/sdk/bin/x86_64-nacl-clang -m64 -D__STDC_LIMIT_MACROS=1 -D__STDC_FORMAT_MACROS=1 -D_GNU_SOURCE=1 -D_POSIX_C_SOURCE=199506 -D_XOPEN_SOURCE=600 -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DDYNAMIC_ANNOTATIONS_PREFIX=NACL_ -DNACL_BUILD_ARCH=x86 -DNACL_BUILD_SUBARCH=64 -I/home/runner/work/native_client/native_client/scons-out/nacl_irt-x86-64/include -I/home/runner/work/native_client/native_client/include-hax -I/home/runner/work/native_client/native_client/src/untrusted/pthread -c -o
UNKNOWN COMPILER
*** BROKEN  run_seccomp_open_errno_test
*** BROKEN  run_ncval_annotate_test
*** BROKEN  run_dynamic_modify_test
*** BROKEN  run_nanosleep_test
*** BROKEN  run_sel_ldr_seccomp_test
*** BROKEN  run_timefuncs_test
*** BROKEN  run_raw_timefuncs_test
*** BROKEN  run_main_thread_pthread_exit_test2
There are 8 broken tests.

Edit: This was unrelated.

[illwieckz]

Ah, it seems to require the DEPS file:

FileNotFoundError: [Errno 2] No such file or directory: '…/native_client/native_client/DEPS'

[illwieckz]

Ah, it seems to require the DEPS file:

FileNotFoundError: [Errno 2] No such file or directory: '…/native_client/native_client/DEPS'

That import is useless.

[illwieckz]

OK, now the only failing test is this one (windows-amd64-mingw):

======================================================================
Stderr for nacl_newlib.run_mmap_atomicity_test:
======================================================================
[7552,784:01:09:15.180000] Native Client module will be loaded at base address 0x000006b100000000

waiting for child thread...
child thread has started.
mmap call #0
checking for write to page...
mmap call #1
checking for write to page...
mmap call #2
checking for write to page...
mmap call #3
…
mmap call #886
checking for write to page...
mmap call #887
checking for write to page...
mmap call #888
checking for write to page...
mmap call #889
checking for write to page...
Killed test due to timeout!

[  FAILED  ] nacl_newlib.run_mmap_atomicity_test (110578 ms)

I have no idea why (help welcome).

[illwieckz]

# * This test is extremely slow on the memcheck bot, which eventually
#   times out, so it is disabled there.  This may be a consequence of
#   running under a VM, since running the test on memcheck locally is
#   fast enough.

Maybe I'm just unlucky?

Failing after 8m

It's supposed to last 10 minutes.

[slipher]

run_mmap_atomicity_test does a sort of hand-off between 2 threads 1000 times. So maybe the progress could be slow with unlucky thread scheduling, if it never manages to get both threads running at once. A possible solution is to add is_flaky=True to the test definition so it doesn't run on CI.