fix build after Mercurial move.
various missing or incorrect files.

R=r
CC=go-dev
http://go/go-review/1014004
diff --git a/src/libmach/executable.c b/src/libmach/executable.c
index 6bde5b5..1455b10 100644
--- a/src/libmach/executable.c
+++ b/src/libmach/executable.c
@@ -514,7 +514,12 @@
 	 */
 	if((hp->e.exechdr.magic & ~DYN_MAGIC)>>16)
 		return 0;
-	entry = beswav(*(uvlong*)&hp->e.exechdr);
+	union {
+		char *p;
+		uvlong *v;
+	} u;
+	u.p = (char*)&hp->e.exechdr;
+	entry = beswav(*u.v);
 
 	pgsize = mach->pgsize;
 	settext(fp, entry, pgsize+fp->hdrsz, hp->e.exechdr.text, fp->hdrsz);