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.
PowerPC kernel now provides a vDSO implementation for time syscall
(commit fcb41a2030abe0eb716ef0798035ef9562097f42). This patch changes
time syscall wrapper to use the vDSO when available. It also changes
the default non vDSO time on PowerPC to use sysdeps/posix/time.c
(since gettimeofday is a vDSO call).
In order for the __kernel_get_tbfreq vDSO call to work the
INTERNAL_VSYSCALL_NCS macro needed to be updated to prevent it from
assuming an integer return type (since the timebase frequency is a 64-bit
value) by specifying the type of the return type as a macro parameter. The
macro then specifically declares the return value as a 'register' (or
implied pair) of the denoted type. The compiler is then informed that this
register (or implied pair) is to be used for the return value.
