Add environment var to skip building libuv backend; use it on manylinux

_setuputils.py

@@ -20,11 +20,13 @@ from setuptools.command.build_ext import build_ext
 
 PYPY = hasattr(sys, 'pypy_version_info')
 WIN = sys.platform.startswith('win')
-CFFI_WIN_BUILD_ANYWAY = os.environ.get("PYPY_WIN_BUILD_ANYWAY")
+
 RUNNING_ON_TRAVIS = os.environ.get('TRAVIS')
 RUNNING_ON_APPVEYOR = os.environ.get('APPVEYOR')
 RUNNING_ON_CI = RUNNING_ON_TRAVIS or RUNNING_ON_APPVEYOR
 
+
+
 LIBRARIES = []
 DEFINE_MACROS = []
 
@@ -82,6 +84,7 @@ def _parse_environ(key):
                      'Please set it to 1, 0 or an empty string' % (key, value))
 
 IGNORE_CFFI = _parse_environ("GEVENT_NO_CFFI_BUILD")
+SKIP_LIBUV = _parse_environ('GEVENT_NO_LIBUV_BUILD')
 
 def _get_config_value(key, defkey, path=None):
     """

scripts/releases/make-manylinux

@@ -14,7 +14,7 @@ if [ -d /gevent -a -d /opt/python ]; then
         rm -rf dist build *.egg-info
         make clean
         $variant/bin/pip install -U cython cffi setuptools greenlet wheel
-        PATH=$variant/bin:$PATH $variant/bin/python setup.py bdist_wheel
+        GEVENT_NO_LIBUV_BUILD=1 PATH=$variant/bin:$PATH $variant/bin/python setup.py bdist_wheel
         auditwheel repair dist/*.whl
     done
     rm -rf dist build *.egg-info

setup.py

@@ -17,6 +17,7 @@ from _setuputils import read_version
 from _setuputils import system
 from _setuputils import PYPY, WIN
 from _setuputils import IGNORE_CFFI
+from _setuputils import SKIP_LIBUV
 from _setuputils import ConfiguringBuildExt
 from _setuputils import BuildFailed
 from _setuputils import cythonize1
@@ -80,8 +81,10 @@ if not WIN:
         LIBEV_CFFI_MODULE
     )
 
-
-cffi_modules.append(LIBUV_CFFI_MODULE)
+if not SKIP_LIBUV:
+    # libuv can't be built on manylinux because it needs glibc >= 2.12
+    # but manylinux has only 2.5, so we set SKIP_LIBUV in the script make-manylinux
+    cffi_modules.append(LIBUV_CFFI_MODULE)
 
 if PYPY:
     install_requires = []