Specify CFLAGS to install fairseq in MacOS

[hudeven]

Summary:
Currently, we installs fairseq by requirements.txt which is equivalent to pip install fairseq

According to https://github.com/pytorch/fairseq, to install fairseq in MacOS, we need to run
CFLAGS="-stdlib=libc++" pip install fairseq

Before this diff:
Can't install PyText in MacOS by
$ ./install_deps

Installing collected packages: click, pycparser, cffi, fastBPE, numpy, regex, portalocker, typing, sacrebleu, torch, tqdm, fairseq, attrs, hypothesis, joblib, typing-extensions, six, setuptools, protobuf, onnx, python-dateutil, certifi, urllib3, idna, chardet, requests, jmespath, docutils, botocore, s3transfer, boto3, pytorch-pretrained-bert, pytz, pandas, scipy, torchtext, wheel, grpcio, werkzeug, markdown, absl-py, tensorboard, sentencepiece, pytext-nlp
Running setup.py install for pycparser ... done
Running setup.py install for fastBPE ... error
ERROR: Command errored out with exit status 1:
command: /Users/stevenliu/workspace/sphinx/pytext/pytext_venv/bin/python3 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-install-x0x9inoi/fastBPE/setup.py'"'"'; file='"'"'/private/var/folders/ sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-install-x0x9inoi/fastBPE/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' install --record /private/var/folders/sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-record-1kds02_a/install-record.txt --single-version-externally-managed --compile --install-headers /Users/stevenliu/workspace/sphinx/pytext/pytext_venv/include/site/python3.7/fastBPE
cwd: /private/var/folders/sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-install-x0x9inoi/fastBPE/
Complete output (16 lines):
running install
running build
running build_py
package init file 'fastBPE/init.py' not found (or not a regular file)
running build_ext
building 'fastBPE' extension
creating build
creating build/temp.macosx-10.7-x86_64-3.7
creating build/temp.macosx-10.7-x86_64-3.7/fastBPE
gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/stevenliu/ anaconda3/include -arch x86_64 -I/Users/stevenliu/anaconda3/include -arch x86_64 -I/Users/stevenliu/workspace/sphinx/pytext/pytext_venv/ include -I/Users/stevenliu/anaconda3/include/python3.7m -c fastBPE/fastBPE.cpp -o build/temp.macosx-10.7-x86_64-3.7/fastBPE/fastBPE.o -std=c++11 -Ofast -pthread
warning: include path for stdlibc++ headers not found; pass '-stdlib=libc++' on the command line to use the libc++ standard library instead [-Wstdlibcxx-not-found]
fastBPE/fastBPE.cpp:603:10: fatal error: 'ios' file not found
#include "ios"
^~~~~
1 warning and 1 error generated.
error: command 'gcc' failed with exit status 1
----------------------------------------
ERROR: Command errored out with exit status 1: /Users/stevenliu/workspace/sphinx/pytext/pytext_venv/bin/python3 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-install-x0x9inoi/fastBPE/setup.py'"'"'; file='"'"'/private/var/folders/sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-install-x0x9inoi/fastBPE/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' install --record /private/var/folders/sg/jcdjt2vn6pndx_d0vmf0l2n15y5jp7/T/pip-record-1kds02_a/install-record.txt --single-version-externally-managed --compile --install-headers /Users/stevenliu/workspace/sphinx/pytext/pytext_venv/include/site/python3.7/fastBPE Check the logs for full command output.

BTW, made activation_venv executable as install_deps

Differential Revision: D18753339

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D18753339

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D18753339

[facebook-github-bot]

This pull request has been merged in 5cb79b7.