FreeBSD/i386 work

This patchset gets Go to pretty much the same state that
FreeBSD/amd64 is in.

R=rsc
https://golang.org/cl/157055
diff --git a/src/pkg/runtime/freebsd/amd64/defs.h b/src/pkg/runtime/freebsd/amd64/defs.h
index 06efcc2..83fd40b 100644
--- a/src/pkg/runtime/freebsd/amd64/defs.h
+++ b/src/pkg/runtime/freebsd/amd64/defs.h
@@ -1,4 +1,4 @@
-// godefs -f -m64 freebsd/defs.c
+// godefs -f -m64 defs.c
 
 // MACHINE GENERATED - DO NOT EDIT.
 
@@ -21,6 +21,28 @@
 // Types
 #pragma pack on
 
+typedef struct Rtprio Rtprio;
+struct Rtprio {
+	uint16 type;
+	uint16 prio;
+};
+
+typedef struct ThrParam ThrParam;
+struct ThrParam {
+	void *start_func;
+	void *arg;
+	int8 *stack_base;
+	uint64 stack_size;
+	int8 *tls_base;
+	uint64 tls_size;
+	int64 *child_tid;
+	int64 *parent_tid;
+	int32 flags;
+	byte pad0[4];
+	Rtprio *rtp;
+	void* spare[3];
+};
+
 typedef struct Sigaltstack Sigaltstack;
 struct Sigaltstack {
 	int8 *ss_sp;