perf tools: Remove xrealloc and ALLOC_GROW

Remove unused xrealloc() and ALLOC_GROW() from libperf.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054801.6158.6204.stgit@devbox


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>