syscall: add #include "funcdata.h" to files modified in last CL

That's what defines GO_ARGS.

TBR=khr
CC=golang-codereviews
https://golang.org/cl/141460043
diff --git a/src/syscall/asm_nacl_amd64p32.s b/src/syscall/asm_nacl_amd64p32.s
index 33f8220..637fafa 100644
--- a/src/syscall/asm_nacl_amd64p32.s
+++ b/src/syscall/asm_nacl_amd64p32.s
@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "textflag.h"
+#include "funcdata.h"
 #include "../runtime/syscall_nacl.h"
 
 //