The new test framework changed the call stacks. The weak attribute
acts as a strong compiler barrier. Some static functions had to be
declared extern as a consequence.
This patch fixes backtrace for PPC32 and PPC64 to correctly handle
signal trampolines. The 'debug/tst-backtrace6.c' also check for
SA_SIGINFO handling, where is triggers another vDSO symbols for PPC32.
Joseph Myers
Florian Weimer
Allan McRae
Adhemerval Zanella