[lldb] refactor PlatformAndroid and make threadsafe (attempt 2) (#159676)
Reattempt at https://github.com/llvm/llvm-project/pull/145382 (cc
@labath). This time setenv() was replaced with set_env()
(https://github.com/llvm/llvm-project/pull/145382#issuecomment-3187227704).
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Co-authored-by: Chad Smith <cssmith@meta.com>