Remove gdb_index_unpack

gdb_index_unpack is not used and can be removed.  The include of
extract-store-integer.h is also no longer needed by this file.

Approved-By: Andrew Burgess <aburgess@redhat.com>

gdb/dwarf2/index-common.h

diff --git a/gdb/dwarf2/index-common.h b/gdb/dwarf2/index-common.h
index b9e0a63..ca37721 100644
--- a/gdb/dwarf2/index-common.h
+++ b/gdb/dwarf2/index-common.h
@@ -20,7 +20,6 @@
 #ifndef GDB_DWARF2_INDEX_COMMON_H
 #define GDB_DWARF2_INDEX_COMMON_H
 
-#include "extract-store-integer.h"
 #include "hashtab.h"
 
 /* The suffix for an index file.  */
@@ -32,15 +31,6 @@
    architecture-independent.  */
 typedef uint32_t offset_type;
 
-/* Unpack a 32-bit little-endian value.  */
-
-static inline offset_type
-gdb_index_unpack (const gdb_byte *value)
-{
-  return (offset_type) extract_unsigned_integer (value, sizeof (offset_type),
-						 BFD_ENDIAN_LITTLE);
-}
-
 /* The hash function for strings in the mapped index.  This is the same as
    SYMBOL_HASH_NEXT, but we keep a separate copy to maintain control over the
    implementation.  This is necessary because the hash function is tied to the