perf annotate: Refactor the code to parse disassemble lines with {l,r}trim()

When parsing disassemble lines, use ltrim() and rtrim() to strip them,
not using just while loop and isspace().

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1491612748-1605-2-git-send-email-treeze.taeung@gmail.com


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