perf symbol: Do not fixup end address of labels

When it loads symbols from an ELF file, it loads label symbols which is
0 size. Sometimes it has the same address with other symbols and might
shadow the original symbols because it fixes up the size of the symbol.

For example, in my system __do_softirq is shadowed and only accepts the
__softirqentry_text_start instead. But it should accept __do_softirq.

$ readelf -sW vmlinux | grep -e __do_softirq -e __softirqentry_text_start
105089: ffffffff82000000 814 FUNC GLOBAL DEFAULT 1 __do_softirq
111954: ffffffff82000000 0 NOTYPE GLOBAL DEFAULT 1 __softirqentry_text_start

$ perf annotate --stdio __do_softirq
Error:
The perf.data data has no samples!

$ perf annotate --stdio __softirqentry_text_start | head
Percent | Source code & Disassembly of vmlinux for cycles (26 samples, percent: local period)
---------------------------------------------------------------------------------------------------
: 0 0xffffffff82000000 <__softirqentry_text_start>:
0.00 : ffffffff82000000: nopl (%rax,%rax)
30.77 : ffffffff82000005: pushq %rbp
3.85 : ffffffff82000006: movq %rsp, %rbp
0.00 : ffffffff82000009: pushq %r15
3.85 : ffffffff8200000b: pushq %r14
3.85 : ffffffff8200000d: pushq %r13
0.00 : ffffffff8200000f: pushq %r12

We can ignore NOTYPE symbols in the symbols__fixup_end() so that it can
pick the __do_softirq() in choose_best_symbol(). This should be fine
since most symbols have either STT_FUNC or STT_OBJECT.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/symbol.c

···
 		 * like in:
 		 *   ffffffffc1937000 T hdmi_driver_init  [snd_hda_codec_hdmi]
 		 */
-		if (prev->end == prev->start) {
+		if (prev->end == prev->start && prev->type != STT_NOTYPE) {
 			const char *prev_mod;
 			const char *curr_mod;