perf annotate: Reset the dso find_symbol cache when removing symbols

perf annotate: Reset the dso find_symbol cache when removing symbols

The 'annotate' tool does some filtering in the entries in a DSO but
forgot to reset the cache done in dso__find_symbol(), cauxing a SEGV:

  [root@zoo ~]# perf annotate netlink_poll
  perf: Segmentation fault
  -------- backtrace --------
  perf[0x526ceb]
  /lib64/libc.so.6(+0x34960)[0x7faedfbe0960]
  perf(rb_erase+0x223)[0x499d63]
  perf[0x4213e9]
  perf[0x4bc123]
  perf[0x4bc621]
  perf[0x4bf26b]
  perf[0x4bc855]
  perf(perf_session__process_events+0x340)[0x4bddc0]
  perf(cmd_annotate+0x6bb)[0x421b5b]
  perf[0x479063]
  perf(main+0x60a)[0x42098a]
  /lib64/libc.so.6(__libc_start_main+0xf0)[0x7faedfbcbfe0]
  perf[0x420aa9]
  [0x0]
  [root@zoo ~]#

Fix it by reseting the find cache when removing symbols.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Fixes: b685ac22b436 ("perf symbols: Add front end cache for DSO symbol lookup")
Link: http://lkml.kernel.org/n/tip-b2y9x46y0t8yem1ive41zqyp@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>