fix warnings when arch lacks get_kernel_syms syscall (like ia64)

libc/sysdeps/linux/common/get_kernel_syms.c

@@ -9,13 +9,13 @@
 
 #include "syscalls.h"
 
-#ifdef __NR_get_kernel_syms
 struct kernel_sym;
+#ifdef __NR_get_kernel_syms
 _syscall1(int, get_kernel_syms, struct kernel_sym *, table);
 #else
 int get_kernel_syms(struct kernel_sym *table)
 {
 	__set_errno(ENOSYS);
-	return (unsigned long)-1;
+	return -1;
 }
 #endif