Don't include cooked-index.h from dwarf2/read.h

dwarf2/read.h includes cooked-index.h, but it doesn't need to.  This
patch removes the inclusion from this header, and adds one to
index-write.c to make up for the absence.

Author: tromey

gdb/dwarf2/index-write.c

@@ -30,6 +30,7 @@
 #include "gdbsupport/scoped_fd.h"
 #include "complaints.h"
 #include "dwarf2/index-common.h"
+#include "dwarf2/cooked-index.h"
 #include "dwarf2.h"
 #include "dwarf2/read.h"
 #include "dwarf2/dwz.h"

gdb/dwarf2/read.h

@@ -23,7 +23,6 @@
 #include <queue>
 #include <unordered_map>
 #include "dwarf2/comp-unit-head.h"
-#include "dwarf2/cooked-index.h"
 #include "dwarf2/file-and-dir.h"
 #include "dwarf2/index-cache.h"
 #include "dwarf2/mapped-index.h"