Custom gevent recipe to fix broken arm64-v8a build

Refs: kivy/python-for-android#1722 (comment)

src/python-for-android/recipes/gevent/__init__.py

@@ -0,0 +1,41 @@
+import re
+
+from pythonforandroid.logger import info
+from pythonforandroid.recipe import CythonRecipe
+
+
+class GeventRecipe(CythonRecipe):
+    version = '1.4.0'
+    url = (
+        'https://pypi.python.org/packages/source/g/gevent/'
+        'gevent-{version}.tar.gz'
+    )
+    depends = ['librt', 'greenlet']
+    patches = ["cross_compiling.patch"]
+
+    def get_recipe_env(self, arch=None, with_flags_in_cc=True):
+        """
+        - Moves all -I<inc> -D<macro> from CFLAGS to CPPFLAGS environment.
+        - Moves all -l<lib> from LDFLAGS to LIBS environment.
+        - Copies all -l<lib> from LDLIBS to LIBS environment.
+        - Fixes linker name (use cross compiler)  and flags (appends LIBS)
+        """
+        env = super().get_recipe_env(arch, with_flags_in_cc)
+        # CFLAGS may only be used to specify C compiler flags,
+        # for macro definitions use CPPFLAGS
+        regex = re.compile(r'(?:\s|^)-[DI][\S]+')
+        env['CPPFLAGS'] = ''.join(re.findall(regex, env['CFLAGS'])).strip()
+        env['CFLAGS'] = re.sub(regex, '', env['CFLAGS'])
+        info('Moved "{}" from CFLAGS to CPPFLAGS.'.format(env['CPPFLAGS']))
+        # LDFLAGS may only be used to specify linker flags,
+        # for libraries use LIBS
+        regex = re.compile(r'(?:\s|^)-l[\w\.]+')
+        env['LIBS'] = ''.join(re.findall(regex, env['LDFLAGS'])).strip()
+        env['LIBS'] += ' {}'.format(
+            ''.join(re.findall(regex, env['LDLIBS'])).strip())
+        env['LDFLAGS'] = re.sub(regex, '', env['LDFLAGS'])
+        info('Moved "{}" from LDFLAGS to LIBS.'.format(env['LIBS']))
+        return env
+
+
+recipe = GeventRecipe()

src/python-for-android/recipes/gevent/cross_compiling.patch

@@ -0,0 +1,26 @@
+diff --git a/_setupares.py b/_setupares.py
+index dd184de6..bb16bebe 100644
+--- a/_setupares.py
++++ b/_setupares.py
+@@ -43,7 +43,7 @@ else:
+ ares_configure_command = ' '.join([
+     "(cd ", quoted_dep_abspath('c-ares'),
+     " && if [ -r ares_build.h ]; then cp ares_build.h ares_build.h.orig; fi ",
+-    " && sh ./configure --disable-dependency-tracking " + _m32 + "CONFIG_COMMANDS= ",
++    " && sh ./configure --host={} --disable-dependency-tracking ".format(os.environ['TOOLCHAIN_PREFIX']) + _m32 + "CONFIG_COMMANDS= ",
+     " && cp ares_config.h ares_build.h \"$OLDPWD\" ",
+     " && cat ares_build.h ",
+     " && if [ -r ares_build.h.orig ]; then mv ares_build.h.orig ares_build.h; fi)",
+diff --git a/_setuplibev.py b/_setuplibev.py
+index 2a5841bf..b6433c94 100644
+--- a/_setuplibev.py
++++ b/_setuplibev.py
+@@ -31,7 +31,7 @@ LIBEV_EMBED = should_embed('libev')
+ # and the PyPy branch will clean it up.
+ libev_configure_command = ' '.join([
+     "(cd ", quoted_dep_abspath('libev'),
+-    " && sh ./configure ",
++    " && sh ./configure --host={} ".format(os.environ['TOOLCHAIN_PREFIX']),
+     " && cp config.h \"$OLDPWD\"",
+     ")",
+     '> configure-output.txt'