[scripts] Remove hard-coded clang version

Bug: http://b/187231324

Instead,
- For local development, invoke build/soong/scripts/get_clang_version.py
to find the current clang version.
- In CI, find llvm-cxxfilt using glob expansion.

Test: development/scripts/symbol.py unittest for local development
      python-stack_core_test on presubmit
Change-Id: Id4258dd791626508520b6a478b8a1b54495ebb11
1 file changed