tools: bpftool: fix potential format truncation

GCC 7 complains:

xlated_dumper.c: In function ‘print_call’:
xlated_dumper.c:179:10: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size between 249 and 253 [-Wformat-truncation=]
     "%+d#%s", insn->off, sym->name);

Add a bit more space to the buffer so it can handle the entire
string and integer without truncation.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

tools/bpf/bpftool/xlated_dumper.h

@@ -49,7 +49,7 @@ struct dump_data {
 	unsigned long address_call_base;
 	struct kernel_sym *sym_mapping;
 	__u32 sym_count;
-	char scratch_buff[SYM_MAX_NAME];
+	char scratch_buff[SYM_MAX_NAME + 8];
 };
 
 void kernel_syms_load(struct dump_data *dd);