DWARF: Add debug_ranges/rnglists tests

.debug_ranges parsing is not well tested [citation needed] because this
section tends to be only used in optimized code, and we don't build
optimized executables in our tests, as they produce unpredictable
results.

This patch aims to add some very simple tests for parsing static range
data, which can serve as a first line of defense in case things break.

I also include one XFAILed test, which demonstrates that we don't
correctly handle mixed DWARF v5 and v4 ranges in a single file.

llvm-svn: 361373