gdb: remove includes from dwarf2/mapped-index.h

They are unused, according to clangd.

Add some includes to other files, which were relying on transitive
includes.

Change-Id: I3bcb4be93b3a18bf44a4068f4067e567f83e1d4f

gdb/dwarf2/cooked-index.c

@@ -18,6 +18,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "dwarf2/cooked-index.h"
+#include "dwarf2/index-common.h"
 #include "dwarf2/read.h"
 #include "dwarf2/stringify.h"
 #include "dwarf2/index-cache.h"

gdb/dwarf2/index-cache.c

@@ -23,6 +23,7 @@
 #include "cli/cli-cmds.h"
 #include "cli/cli-decode.h"
 #include "command.h"
+#include "dwarf2/index-common.h"
 #include "gdbsupport/scoped_mmap.h"
 #include "gdbsupport/pathstuff.h"
 #include "dwarf2/index-write.h"

gdb/dwarf2/mapped-index.h

@@ -20,8 +20,6 @@
 #ifndef GDB_DWARF2_MAPPED_INDEX_H
 #define GDB_DWARF2_MAPPED_INDEX_H
 
-#include "dwarf2/index-common.h"
-#include "language.h"
 #include "quick-symbol.h"
 
 class cooked_index;

gdb/dwarf2/read-gdb-index.c

@@ -22,6 +22,7 @@
 #include "cli/cli-cmds.h"
 #include "cli/cli-style.h"
 #include "complaints.h"
+#include "dwarf2/index-common.h"
 #include "dwz.h"
 #include "event-top.h"
 #include "gdb/gdb-index.h"