Rework libxml2 recipe and update version

Actions taken:
  - replace double quotes to single quotes because I think that it's more readable
  - fixed imports
  - shortened lines

pythonforandroid/recipes/libxml2/__init__.py

@@ -1,53 +1,58 @@
-from pythonforandroid.toolchain import Recipe, shprint, shutil, current_directory
+from pythonforandroid.recipe import Recipe
+from pythonforandroid.toolchain import shprint, shutil, current_directory
 from os.path import exists, join
 import sh
 
 
 class Libxml2Recipe(Recipe):
-    version = "2.7.8"
-    url = "http://xmlsoft.org/sources/libxml2-{version}.tar.gz"
+    version = '2.9.8'
+    url = 'http://xmlsoft.org/sources/libxml2-{version}.tar.gz'
     depends = []
-    patches = ["add-glob.c.patch"]
+    patches = ['add-glob.c.patch']
 
     def should_build(self, arch):
         super(Libxml2Recipe, self).should_build(arch)
-        return not exists(join(self.ctx.get_libs_dir(arch.arch), "libxml2.a"))
+        return not exists(
+            join(self.get_build_dir(arch.arch), '.libs', 'libxml2.a'))
 
     def build_arch(self, arch):
         super(Libxml2Recipe, self).build_arch(arch)
         env = self.get_recipe_env(arch)
         with current_directory(self.get_build_dir(arch.arch)):
-            env["CC"] += " -I%s" % self.get_build_dir(arch.arch)
-            shprint(
-                sh.Command("./configure"),
-                "--host=arm-linux-eabi",
-                "--without-modules",
-                "--without-legacy",
-                "--without-history",
-                "--without-debug",
-                "--without-docbook",
-                "--without-python",
-                "--without-threads",
-                "--without-iconv",
-                _env=env,
-            )
+
+            if not exists('configure'):
+                shprint(sh.Command('./autogen.sh'), _env=env)
+            shprint(sh.Command('autoreconf'), '-vif', _env=env)
+            build_arch = shprint(
+                sh.gcc, '-dumpmachine').stdout.decode('utf-8').split('\n')[0]
+            shprint(sh.Command('./configure'),
+                    '--build=' + build_arch,
+                    '--host=' + arch.command_prefix,
+                    '--target=' + arch.command_prefix,
+                    '--without-modules',
+                    '--without-legacy',
+                    '--without-history',
+                    '--without-debug',
+                    '--without-docbook',
+                    '--without-python',
+                    '--without-threads',
+                    '--without-iconv',
+                    '--disable-shared',
+                    '--enable-static',
+                    _env=env)
 
             # Ensure we only build libxml2.la as if we do everything
             # we'll need the glob dependency which is a big headache
             shprint(sh.make, "libxml2.la", _env=env)
-            shutil.copyfile(
-                ".libs/libxml2.a", join(self.ctx.get_libs_dir(arch.arch), "libxml2.a")
-            )
+
+            shutil.copyfile('.libs/libxml2.a',
+                            join(self.ctx.libs_dir, 'libxml2.a'))
 
     def get_recipe_env(self, arch):
         env = super(Libxml2Recipe, self).get_recipe_env(arch)
-        env["CONFIG_SHELL"] = "/bin/bash"
-        env["SHELL"] = "/bin/bash"
-        env[
-            "CC"
-        ] = "arm-linux-androideabi-gcc -DANDROID -mandroid -fomit-frame-pointer --sysroot={}".format(
-            self.ctx.ndk_platform
-        )
+        env['CONFIG_SHELL'] = '/bin/bash'
+        env['SHELL'] = '/bin/bash'
+        env['CC'] += ' -I' + self.get_build_dir(arch.arch)
         return env