meson: Simplify script execution

- Let Meson's find_program() do the heavy lifting.
- Make scripts executable.
- Add shebang to scripts.

lib/build.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 from pathlib import Path
 import shutil

lib/meson.build

@@ -38,8 +38,7 @@ custom_target('js',
   input: sources,
   output: outputs,
   command: [
-    python,
-    files('build.py'),
+    find_program('build.py'),
     '@OUTDIR@',
     '@PRIVATE_DIR@',
     npm,

meson.build

@@ -4,10 +4,8 @@ project('frida-node', 'cpp',
 
 node = find_program('node')
 npm = find_program('npm')
-python = import('python').find_installation()
 
-version = run_command(python, files('scripts' / 'detect-version.py'),
-  files('package.json'),
+version = run_command(find_program('scripts' / 'detect-version.py'), files('package.json'),
   capture: true,
   check: true,
 ).stdout().strip()
@@ -51,7 +49,7 @@ else
 endif
 
 message('Fetching ABI bits')
-metadata = run_command(python, files('scripts' / 'fetch-abi-bits.py'),
+metadata = run_command(find_program('scripts' / 'fetch-abi-bits.py'),
   runtime, target, gyp_os, gyp_arch,
   node, npm, meson.current_build_dir(),
   capture: true,
@@ -135,8 +133,7 @@ custom_target('prebuild',
   input: [binding],
   output: [f'frida-v@version@-@runtime@-v@abi@-@node_platform@-@[email protected]'],
   command: [
-    python,
-    files('scripts' / 'package.py'),
+    find_program('scripts' / 'package.py'),
     '@INPUT@',
     '@OUTPUT@',
   ],

scripts/detect-version.py

@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 import json
 from pathlib import Path
 import sys

scripts/fetch-abi-bits.py

@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 from dataclasses import dataclass
 from io import BytesIO
 import json

scripts/install.js

@@ -1,3 +1,5 @@
+#!/usr/bin/env node
+
 const { execSync } = require('child_process');
 const fs = require('fs');
 const path = require('path');