FFI: Need to treat strlen() as a load.

src/lj_ircall.h

@@ -168,7 +168,7 @@ typedef struct CCallInfo {
   _(FFI,	lj_carith_powi64,	ARG2_64,   N, I64, CCI_NOFPRCLOBBER) \
   _(FFI,	lj_carith_powu64,	ARG2_64,   N, U64, CCI_NOFPRCLOBBER) \
   _(FFI,	lj_cdata_setfin,	2,        FN, P32, CCI_L) \
-  _(FFI,	strlen,			1,         N, INTP, 0) \
+  _(FFI,	strlen,			1,         L, INTP, 0) \
   _(FFI,	memcpy,			3,         S, PTR, 0) \
   _(FFI,	memset,			3,         S, PTR, 0) \
   _(FFI,	lj_vm_errno,		0,         S, INT, CCI_NOFPRCLOBBER) \