Fix a g++ 4.5 warning, http://bugzilla.redhat.com/668178

--- gdbm-1.8.3/gdbm.proto
+++ gdbm-1.8.3/gdbm.proto
@@ -60,7 +60,7 @@ typedef struct {
 
 
 /* The file information header. This is good enough for most applications. */
-typedef struct {int dummy[10];} *GDBM_FILE;
+typedef struct __GDBM_FILE_STRUC {int dummy[10];} *GDBM_FILE;
 
 /* Determine if the C(++) compiler requires complete function prototype  */
 #ifndef __P