spu2x: use std::abs (c abs support only integer)
gsdx: miss break / inline function in header
pcsx2: don't hide base function

As far as I understand you can't mix virtual (select at runtime) and
overloading (select at compile time).
pcsx2: be sure that variables are initialized
pcsx2: remove/disable brace warning
cmake: remove a specific warning for clang
gcc: support address sanitizer