perf powerpc: Generate system call table from asm/unistd.h

perf powerpc: Generate system call table from asm/unistd.h

This should speed up accessing new system calls introduced with the
kernel rather than waiting for libaudit updates to include them.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20180129083417.31240-3-ravi.bangoria@linux.vnet.ibm.com
[ Made it generate syscall_32.c as well to fix the build on 32-bit ppc ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>