perf annotate: Fix AArch64 comment char

perf annotate: Fix AArch64 comment char

The commit 0fcb1da4aba "perf annotate: AArch64 support" blindly copied
the comment character from the original:

            https://lkml.org/lkml/2016/5/19/461

whereas that same commit shows objdump output utilizing the C++ style
"//" as the comment delimeter.  Since '/' doesn't occur elsewhere in
objdump output, we retain the single character check, but fix it to be
'/'.

Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Chris Riyder <chris.ryder@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 0fcb1da4aba6 ("perf annotate: AArch64 support")
Link: http://lkml.kernel.org/r/20170503131356.be88f977094fb3fa0f49b99d@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>