- Use boost::stacktrace instead of libbacktrace so that we get can get
  callstacks on Windows as well. Note that on non-Windows, we tell
  boost::stacktrace to use libbacktrace.

- REACTOR_EMIT_DEBUG_INFO can now be enabled on all platforms

- Fix RR_LOG not building on MSVC by using __FUNCSIG__ instead of
  __PRETTY_FUNCTION__.

- Enable CMake option REACTOR_EMIT_PRINT_LOCATION so that EmitLocation
  in LLVMReactorDebugInfo.cpp injects printfs with func/file/line.
  Sample output:
    rr> sw::Blitter::generate [c:\src\swiftshader\src\renderer\blitter.cpp:1303]
    rr> sw::Blitter::generate [c:\src\swiftshader\src\renderer\blitter.cpp:1304]
    rr> sw::Blitter::ComputeOffset [c:\src\swiftshader\src\renderer\blitter.cpp:1148]
    rr> sw::Blitter::generate [c:\src\swiftshader\src\renderer\blitter.cpp:1312]
    rr> sw::Blitter::generate [c:\src\swiftshader\src\renderer\blitter.cpp:1314]
    rr> sw::SetupRoutine::edge [c:\src\swiftshader\src\shader\setuproutine.cpp:566]

Bug: b/131425026
Change-Id: Ia3b78652f4a76dcd6597ce2df61a236c4a90acc2
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30030Tested-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>