Auto merge of #21366 - jdm:android-ndk-stack, r=paul

Add ndk-stack mach command

This makes it much easier to get usable symbols from logcat output that includes a crash.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #20442
- [x] These changes do not require tests because it's a mach command

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python/servo/devenv_commands.py

@@ -14,6 +14,7 @@ from time import time
 import sys
 import urllib2
 import json
+import subprocess
 
 from mach.decorators import (
     CommandArgument,
@@ -227,3 +228,26 @@ class MachCommands(CommandBase):
 
         with cd(self.context.topdir):
             return self.call_rustup_run(["cargo", "fetch"], env=self.build_env())
+
+    @Command('ndk-stack',
+             description='Invoke the ndk-stack tool with the expected symbol paths',
+             category='devenv')
+    @CommandArgument('--release', action='store_true', help="Use release build symbols")
+    @CommandArgument('--target', action='store', default="armv7-linux-androideabi",
+                     help="Build target")
+    @CommandArgument('logfile', action='store', help="Path to logcat output with crash report")
+    def stack(self, release, target, logfile):
+        if not path.isfile(logfile):
+            print(logfile + " doesn't exist")
+            return -1
+        env = self.build_env(target=target)
+        ndk_stack = path.join(env["ANDROID_NDK"], "ndk-stack")
+        sym_path = path.join(
+            "target",
+            target,
+            "release" if release else "debug",
+            "apk",
+            "obj",
+            "local",
+            "armeabi-v7a")
+        print(subprocess.check_output([ndk_stack, "-sym", sym_path, "-dump", logfile]))