In #124846 the symbolizer was changed to ignore 0-column entries, which
lead to a slightly different representation in the stack traces. This
patch addresses these differences.
Not sure if the difference in kernel_trap.c is also a result of this
change or not.
Can be tracked separate from this, after the bots are back to green.
It appears that the RUNTIMES build prefers the x86-64-unknown-linux-gnu
triple notation for the host. This fixes runtime / test breakages when
compiler-rt is used as the CLANG_DEFAULT_RTLIB.
The kernel names for OpenMP are manually mangled and not ideal when we
report something to the user. We demangle them now, providing the
function and line number of the target region, together with the actual
kernel name.