build: python3 support for configure

[rvagg]

Discovered while messing with some infra switching things around to python3. On Linux, if you call configure directly with a python3 (not letting it find python for you) and have LC_ALL=C set, as we do in some of our infra, apparently open() defaults to ascii. This is a problem for icu version detection because there's a © at the top of deps/icu-small/source/common/unicode/uvernum.h which it reads to find major version number.

$ LC_ALL=C python3 ./configure.py
Traceback (most recent call last):
  File "./configure.py", line 1660, in <module>
    configure_intl(output)
  File "./configure.py", line 1498, in configure_intl
    for line in open(uvernum_h).readlines():
  File "/usr/lib/python3.6/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 3: ordinal not in range(128)

This change fixes it and makes it work for Python 2 & 3. Although I don't really know what I'm doing with the conversion back to ascii for later compatibility so someone who knows better should check.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26127/

[targos]

This is similar to #30023

[rvagg]

indeed it is! but in this case the return value needs to mix with non-utf8 strings and python2 borks at that, hence the str(x).

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26128/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26129/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26130/

[cclauss]

LGTM.

Minor nit: for line in open(uvernum_h).readlines(): leaves the filehandle open so the preferred approach is:

with open(uvernum_h) as in_file:
    for line in in_file:

because the with open() as context manager will automate the filehandle close().

[rvagg]

ok, have tried that approach, ptal @cclauss

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26131/

[cclauss]

I have already approved. For those who want to dig in...
https://www.python.org/dev/peps/pep-0538/ and https://www.python.org/dev/peps/pep-0540/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26176/

[rvagg]

Landed in 779d7ef