NSEC3HashName() is used as a boolean return, so actually convert
it to this, and avoid returning pointer to the stack that would
not be dereferenced.

Index: external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.c
===================================================================
RCS file: /cvsroot/src/external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.c,v
retrieving revision 1.9
diff -p -u -r1.9 DNSCommon.c
--- external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.c	11 Apr 2018 18:33:48 -0000	1.9
+++ external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.c	12 Apr 2021 21:11:44 -0000
@@ -1160,7 +1160,7 @@ mDNSexport mStatus DNSNameToLowerCase(do
     return mStatus_NoError;
 }
 
-mDNSexport const mDNSu8 *NSEC3HashName(const domainname *name, rdataNSEC3 *nsec3, const mDNSu8 *AnonData, int AnonDataLen,
+mDNSexport mDNSBool NSEC3HashName(const domainname *name, rdataNSEC3 *nsec3, const mDNSu8 *AnonData, int AnonDataLen,
     const mDNSu8 hash[NSEC3_MAX_HASH_LEN], int *dlen)
 {
     AlgContext *ctx;
@@ -1175,7 +1175,7 @@ mDNSexport const mDNSu8 *NSEC3HashName(c
     if (DNSNameToLowerCase((domainname *)name, &lname) != mStatus_NoError)
     {
         LogMsg("NSEC3HashName: ERROR!! DNSNameToLowerCase failed");
-        return mDNSNULL;
+        return mDNSfalse;
     }
 
     digest = lname.c;
@@ -1190,7 +1190,7 @@ mDNSexport const mDNSu8 *NSEC3HashName(c
         if (!ctx)
         {
             LogMsg("NSEC3HashName: ERROR!! Cannot allocate context");
-            return mDNSNULL;
+            return mDNSfalse;
         }
 
         AlgAdd(ctx, digest, digestlen);
@@ -1208,7 +1208,7 @@ mDNSexport const mDNSu8 *NSEC3HashName(c
         AlgDestroy(ctx);
     }
     *dlen = digestlen;
-    return digest;
+    return mDNStrue;
 }
 
 // Notes on UTF-8:
Index: external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.h
===================================================================
RCS file: /cvsroot/src/external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.h,v
retrieving revision 1.2
diff -p -u -r1.2 DNSCommon.h
--- external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.h	11 Apr 2018 18:33:48 -0000	1.2
+++ external/apache2/mDNSResponder/dist/mDNSCore/DNSCommon.h	12 Apr 2021 21:11:44 -0000
@@ -231,7 +231,7 @@ extern mDNSu8 *putDNSSECOption(DNSMessag
 extern int baseEncode(char *buffer, int blen, const mDNSu8 *data, int len, int encAlg);
 extern void NSEC3Parse(const ResourceRecord *const rr, mDNSu8 **salt, int *hashLength, mDNSu8 **nxtName, int *bitmaplen, mDNSu8 **bitmap);
 
-extern const mDNSu8 *NSEC3HashName(const domainname *name, rdataNSEC3 *nsec3, const mDNSu8 *AnonData, int AnonDataLen,
+extern mDNSBool NSEC3HashName(const domainname *name, rdataNSEC3 *nsec3, const mDNSu8 *AnonData, int AnonDataLen,
     const mDNSu8 hash[NSEC3_MAX_HASH_LEN], int *dlen);
 
 // ***************************************************************************