perf alias: Rebuild alias expression string to make it comparable

perf alias: Rebuild alias expression string to make it comparable

PMU alias definitions in sysfs files may have spaces, newlines and
numbers with leading zeroes. Some alias definitions may also appear in
JSON files without spaces, etc.

Scan alias definitions and remove leading zeroes, spaces, newlines, etc
and rebuild string to make alias->str member comparable.

s390 for example  has terms specified as event=0x0091 (read from files
../<PMU>/events/<FILE> and terms specified as event=0x91 (read from JSON
files).

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180615101105.47047-2-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>