Include bcache.h from objfiles.h

objfiles.h needs "struct bcache" to be complete, so it should include
bcache.h.  This patch implements this.

Tested by rebuilding.

gdb/ChangeLog
2019-03-23  Tom Tromey  <tom@tromey.com>

	* objfiles.h: Include bcache.h.

Author: tromey

gdb/ChangeLog

@@ -1,3 +1,7 @@
+2019-03-23  Tom Tromey  <tom@tromey.com>
+
+	* objfiles.h: Include bcache.h.
+
 2019-03-23  Tom Tromey  <tom@tromey.com>
 
 	* linespec.c (get_current_search_block): Use

gdb/objfiles.h

@@ -32,8 +32,8 @@
 #include <vector>
 #include "common/next-iterator.h"
 #include "common/safe-iterator.h"
+#include "bcache.h"
 
-struct bcache;
 struct htab;
 struct objfile_data;
 struct partial_symbol;