i18n module: Invoke itstool with the full command line

Certain envs may not support invoking itstool by itself directly as a script
as shebang lines are not supported, such as under cmd.exe shells on Windows,
that are normally used for Visual Studio (and the like, such as clang-cl)
builds.

This will call the corresponding interpreter to invoke itstool when needed, so
that itstool can be properly run, even if shebang lines are not supported by
the env.

This will fix building appstream on Windows using clang-cl, for instance.

mesonbuild/modules/i18n.py

@@ -14,6 +14,7 @@
 from __future__ import annotations
 
 from os import path
+import shlex
 import typing as T
 
 from . import ExtensionModule, ModuleReturnValue, ModuleInfo
@@ -360,11 +361,14 @@ def itstool_join(self, state: 'ModuleState', args: T.List['TYPE_var'], kwargs: '
         command: T.List[T.Union[str, build.BuildTarget, build.CustomTarget,
                                 build.CustomTargetIndex, 'ExternalProgram', mesonlib.File]] = []
         command.extend(state.environment.get_build_command())
+
+        itstool_cmd = self.tools['itstool'].get_command()
+        # TODO: python 3.8 can use shlex.join()
         command.extend([
             '--internal', 'itstool', 'join',
             '-i', '@INPUT@',
             '-o', '@OUTPUT@',
-            '--itstool=' + self.tools['itstool'].get_path(),
+            '--itstool=' + ' '.join(shlex.quote(c) for c in itstool_cmd),
         ])
         if its_files:
             for fname in its_files:

mesonbuild/scripts/itstool.py

@@ -17,6 +17,7 @@
 import argparse
 import subprocess
 import tempfile
+import shlex
 import shutil
 import typing as T
 
@@ -56,7 +57,7 @@ def run_join(build_dir: str, itstool: str, its_files: T.List[str], mo_files: T.L
             shutil.copy(mo_file, tmp_mo_fname)
             locale_mo_files.append(tmp_mo_fname)
 
-        cmd = [itstool]
+        cmd = shlex.split(itstool)
         if its_files:
             for fname in its_files:
                 cmd.extend(['-i', fname])