[arch-dev-public] Default DEBUG_CFLAGS/CXXFLAGS provided with pacman 4.1

[Jan Alexander Steffens]

With pacman 4.1 just around the corner, we'll be getting support for
split debug information soon.

I would like to recommend "-gdwarf-4 -fvar-tracking-assignments" as
our default debug flags in makepkg.conf. These flags should allow for
better debug information in the presence of optimization (less <value
optimized out>; see man gcc).

Thoughts?