objtool: Fix off-by-one in symbol_by_offset()

Sometimes, WARN_FUNC() and other users of symbol_by_offset() will
associate the first instruction of a symbol with the symbol preceding
it.  This is because symbol->offset + symbol->len is already outside of
the symbol's range.

Fixes: 2a362ecc ("objtool: Optimize find_symbol_*() and read_symbols()")
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

tools/objtool/elf.c

@@ -105,7 +105,7 @@ static int symbol_by_offset(const void *key, const struct rb_node *node)
 
 	if (*o < s->offset)
 		return -1;
-	if (*o > s->offset + s->len)
+	if (*o >= s->offset + s->len)
 		return 1;
 
 	return 0;