Coverity defects

12811: Unused pointer value
       preop_modrdn (plugins/uiduniq/uid.c)
       Removed unused variable "dn".

12812: Unused pointer value
       ldbm_back_next_search_entry_ext (slapd/back-ldbm/ldbm_search.c)
       Removed unused variable "base".

12813: Uninitialized pointer read
       string_values2keys (plugins/syntaxes/string.c)
       Commit f6b74ad18a52720c4558d4a46cbb2eeb21109033 missed to set
       an value bvp for the newly added case ((syntax & SYNTAX_DN) &&
       (value_flags & SLAPI_ATTR_FLAG_NORMALIZED_CES)), which caused
       the uninitialized pointer read.  This patch sets bvp for all
       3 cases.

ldap/servers/plugins/syntaxes/string.c

@@ -605,6 +605,7 @@ string_values2keys( Slapi_PBlock *pb, Slapi_Value **bvals,
 				/* This dn value is case-normalized */
 				value_flags &= ~SLAPI_ATTR_FLAG_NORMALIZED_CES;
 				value_flags |= SLAPI_ATTR_FLAG_NORMALIZED_CIS;
+				bvp = slapi_value_get_berval(bvdup);
 			} else {
 				bvp = slapi_value_get_berval(*bvlp);
 			}

ldap/servers/plugins/uiduniq/uid.c

@@ -862,7 +862,6 @@ preop_modrdn(Slapi_PBlock *pb)
     int err;
     char *markerObjectClass=NULL;
     char *requiredObjectClass=NULL;
-    const char *dn = NULL;
     Slapi_DN *sdn = NULL;
     Slapi_DN *superior;
     char *rdn;
@@ -913,8 +912,6 @@ preop_modrdn(Slapi_PBlock *pb)
     err = slapi_pblock_get(pb, SLAPI_MODRDN_TARGET_SDN, &sdn);
     if (err) { result = uid_op_error(31); break; }
 
-    dn = slapi_sdn_get_dn(sdn);
-
     /* Get superior value - unimplemented in 3.0/4.0/5.0 DS */
     err = slapi_pblock_get(pb, SLAPI_MODRDN_NEWSUPERIOR_SDN, &superior);
     if (err) { result = uid_op_error(32); break; }

ldap/servers/slapd/back-ldbm/ldbm_search.c

@@ -1327,7 +1327,6 @@ ldbm_back_next_search_entry_ext( Slapi_PBlock *pb, int use_extension )
     int                    managedsait;
     Slapi_Attr             *attr;
     Slapi_Filter           *filter;
-    const char             *base;
     back_search_result_set *sr;
     ID                     id;
     struct backentry       *e;
@@ -1380,7 +1379,6 @@ ldbm_back_next_search_entry_ext( Slapi_PBlock *pb, int use_extension )
                                "Null target DN", 0, NULL );
         return( -1 );
     }
-    base = slapi_sdn_get_dn(basesdn);
 
     if (sr->sr_current_sizelimit >= 0) {
         /*