libbpf-tools: Fix list_syscalls() prototype return type

The function list_syscalls() in syscall_helpers.c returns an integer value,
but its prototype in syscall_helpers.h declared a void return type.

This commit corrects the function prototype in syscall_helpers.h to match
its implementation, changing the return type from void to int.

Fixes: f3fbeb4 ("libbpf-tools: convert BCC syscount to BPF CO-RE version")
Signed-off-by: Ism Hong <[email protected]>

Author: ismhong

libbpf-tools/syscall_helpers.h

@@ -6,7 +6,7 @@
 
 void init_syscall_names(void);
 void free_syscall_names(void);
-void list_syscalls(void);
+int list_syscalls(void);
 int syscall_name(unsigned n, char *buf, size_t size);
 
 #endif /* __SYSCALL_HELPERS_H */