Generate DWARF for HelperSDT/_HelperSDT*.so

Generate DWARF for HelperSDT/_HelperSDT*.so

Python Extension Flags Reduction effort [1] dropped GCC -g switch
from the build and linker flags (CFLAGS and LDFLAGS) saved internally
in the Python interpreter for use by distutils and other build systems.

For systemtap this means that the expected debugging symbols weren't
generated for the Helper SDT python module, e.g.:

/usr/lib/debug/usr/lib64/python3.12/site-packages/HelperSDT/_HelperSDT.\
cpython-312-x86_64-linux-gnu.so-5.1-7.el10.x86_64.debug
in systemtap-runtime-python3-debuginfo ... is missing debugging symbols.

To generate the needed debugging symbols, the -g switch  needs to be
passed explicitly to the Helper SDT gen script via extra_compile_args.

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[1] https://fedoraproject.org/wiki/Changes/Python_Extension_Flags_Reduction