BPF: make 'pseudo' function return pointer

'pseudo' function returns u64. However, in fact it returns pointers.
It makes difference for 32-bit systems. The generated IR
has additional trunc instruction, which may make further problems,
remote: when passed to eBPF verifier.

This patch is made to handle similar change in llvm.

Change-Id: I4a691bdfa4b10b207197941c589026997b62f8fe

src/cc/export/helpers.h

@@ -381,7 +381,7 @@ u64 load_dword(void *skb, u64 off) {
 void bpf_store_byte(void *skb, u64 off, u64 val) asm("llvm.bpf.store.byte");
 void bpf_store_half(void *skb, u64 off, u64 val) asm("llvm.bpf.store.half");
 void bpf_store_word(void *skb, u64 off, u64 val) asm("llvm.bpf.store.word");
-u64 bpf_pseudo_fd(u64, u64) asm("llvm.bpf.pseudo");
+void *bpf_pseudo_fd(u64, u64) asm("llvm.bpf.pseudo");
 
 static inline void __attribute__((always_inline))
 bpf_store_dword(void *skb, u64 off, u64 val) {