Include pch header automatically and on-demand

[Kojoley]

Previously it was needed to include pch header in every source file, but Clang does it automatically making the usage non-uniform. It is also a very noisy process to add pch header to an existing project. Automatic on-demand header inclusion solves both issues.

[Kojoley]

The CI failure seems to be intermittent, and I am pretty sure they are not caused by the PR. Could be a bug in B2, try adding ASAN/UBSAN to FreeBSD builds.

[grafikrobot]

The CI failure seems to be intermittent, and I am pretty sure they are not caused by the PR. Could be a bug in B2, try adding ASAN/UBSAN to FreeBSD builds.

There is definitely an asan and memory leak problem hiding. I've run it with asan before locally. But haven't deciphered the issue. Other than it has to do with the response file engine changes I did.

[Kojoley]

The CI failure seems to be intermittent, and I am pretty sure they are not caused by the PR. Could be a bug in B2, try adding ASAN/UBSAN to FreeBSD builds.

There is definitely an asan and memory leak problem hiding. I've run it with asan before locally. But haven't deciphered the issue. Other than it has to do with the response file engine changes I did.

Memory leaks are bad, but they cannot be a reason for the test fails. I tried to understand what the test is about, but it tests undocumented -p parameter. I guess, for some reason, on FreeBSD workers echo "stderr" 1>&2 sometimes redirects data into a blackhole (the stderr message does not appear neither on stderr nor on stdout), or B2 sometimes do not pump all the stderr data

b2/test/core_action_output.py

Line 25 in 9552adf

$(prefix)stderr$(suffix) 1>&2