Makefile: make unstripped libtailscale and debug symbols

- Added Makefile targets to build an unstripped version of the libtailscale AAR.
- Extracted the native .so (libgojni.so) from the unstripped AAR.
- Generated a debug symbols file (libgojni.so.debug) using llvm-objcopy with --only-keep-debug.
- Stripped the native library (libgojni.so.stripped) with --strip-debug and repackaged the final AAR.

This allows the build chain to produce a stripped AAR for the app and a separate debug symbols file that can be uploaded to Google Play for crash deobfuscation.

Signed-off-by: kari-ts <[email protected]>
Updates tailscale/tailscale#15210

Author: kari-ts

.gitignore

@@ -35,6 +35,13 @@ tailscale.jks
 .vscode
 .idea
 
+# Native libraries
+*.stripped
+*.unstripped
+
+# Debug symbols
+*.debug
+
 libtailscale.aar
 libtailscale-sources.jar
 .DS_Store