[llvm-symbolizer][test] Extract tests from llvm-symbolizer.test and simplify (#2)

[llvm-symbolizer][test] Extract tests from llvm-symbolizer.test and simplify (#2)

This is the third of a series of patches simplifying llvm-symbolizer
tests. See r352752 and r352753 for the previous two. This patch splits
out a number of distinct test cases from llvm-symbolizer.test into
separate tests, and simplifies them in various ways including:

1) using --obj/positional arguments for the input file and addresses
   instead of stdin,
2) using runtime-generated inputs rather than a pre-canned binary, and
3) testing more specifically (i.e. checking only what is interesting to
   the behaviour changed in the original commit for that test case).

This patch also removes the test case for using --obj. The
tools/llvm-symbolizer/basic.s test already tests this case. Finally,
this patch adds a simple test case to the demangle switch test case to
show that demangling happens by default.

See https://bugs.llvm.org/show_bug.cgi?id=40070#c1 for the motivation.

Reviewed by: dblaikie

Differential Revision: https://reviews.llvm.org/D57446

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@352754 91177308-0d34-0410-b5e6-96231b3b80d8