perf probe: Show correct statement line number by perf probe -l

The dwarf_getsrc_die() can return the line which is not a statement nor
the least line number among the lines which shares same address.

This can lead perf probe --list shows incorrect line number for probed
address.

To fix this, this introduces cu_getsrc_die() which returns only a
statement line and which is the least line number (we call it the
representive line for an address), and use it in cu_find_lineinfo().

Also, if the given address is the entry address of a real function,
cu_find_lineinfo() returns the function declared line number instead of
the start line number of the function body.

For example, without this change perf probe -l shows incorrect line as
below.

  # perf probe -a kernel_read:2
  Added new event:
    probe:kernel_read    (on kernel_read:2)

  You can now use it in all perf tools, such as:

  	perf record -e probe:kernel_read -aR sleep 1

  # perf probe -l
    probe:kernel_read    (on kernel_read:1@linux-5.0.0/fs/read_write.c)

With this fix, it shows correct line number as below;

  # perf probe -l
    probe:kernel_read    (on kernel_read:2@linux-5.0.0/fs/read_write.c)

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Link: http://lore.kernel.org/lkml/157406471067.24476.17463149618465494448.stgit@devnote2


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