BUG/MINOR: syscall: fix NR_accept4 system call on sparc/linux

An invalid copy-paste called it NR_splice instead of NR_accept4.
This does not lead to real issues because if this define is used,
then the code cannot compile since NR_accept4 is still missing.
diff --git a/include/common/syscall.h b/include/common/syscall.h
index 3ccbf5a..659b0ca 100644
--- a/include/common/syscall.h
+++ b/include/common/syscall.h
@@ -131,7 +131,7 @@
 #if defined(__x86_64__)
 #define __NR_accept4            288
 #elif defined(__sparc__) || defined(__sparc64__)
-#define __NR_splice             323
+#define __NR_accept4            323
 #else
 #define ACCEPT4_USE_SOCKETCALL    1
 #ifndef SYS_ACCEPT4