Always perform == or != operation on cmp function result

Although not required to address bad code generation in
some versions of gcc 9 and 10, a coding style that requires
explicit comparison of the result to zero before use is
both clearer and would have avoided the generation of bad
code.

This change converts all use of cmp function usage from

```
    if (strcmp(a, b) || !strcmp(c, d)) ...
```

to

```
    if (strcmp(a, b) != 0 || strcmp(c, d)) == 0
```

for all C library cmp functions and related:

 - strcmp(), strncmp()
 - strcasecmp(), strncasecmp()
 - stricmp(), strnicmp()
 - memcmp()

Change-Id: Ic60c15e1e3a07e4faaf10648eefe3adae2543188

appl/dceutils/k5dcecon.c

@@ -163,8 +163,8 @@ int k5dcesession(luid, pname, tgt, ppag, tflags)
 /*
  * (but root has the ffffffff which we are not interested in)
  */
-    if (!strncmp(direntp->d_name,"dcecred_",8)
-         && (strlen(direntp->d_name) == 16)) {
+    if (strncmp(direntp->d_name,"dcecred_",8) == 0 &&
+        (strlen(direntp->d_name) == 16)) {
 
       /* looks like a cache name, lets do the stat, etc */
 
@@ -246,7 +246,7 @@ int k5dcematch(luid, pname, ccname, sizep, tgt)
 
   /* DEEDEBUG2("k5dcematch called: cache=%s\n",ccname+38); */
 
-  if (!strncmp(ccname,"FILE:",5)) {
+  if (strncmp(ccname,"FILE:",5) == 0) {
 
     strcpy(ccdata,ccname+5);
     strcat(ccdata,".data");
@@ -343,7 +343,7 @@ int k5dcegettgt(pcache, ccname, pname, tgt)
 
   DEEDEBUG2("Unparsed to \"%s\"\n", kusername);
   DEEDEBUG2("pname is \"%s\"\n", pname);
-  if (strcmp(kusername, pname)) {
+  if (strcmp(kusername, pname) != 0) {
    DEEDEBUG("Principals not equal\n");
    goto return1;
   }
@@ -574,7 +574,7 @@ int k5dcecreate(luid, luser, pname, krbtgt)
     }
 
 
-    if (!strcmp(urealm,defrealm)) {
+    if (strcmp(urealm,defrealm) == 0) {
         strcpy(username,pname);
     } else {
         strcpy(username,"/.../");

appl/kf/kf.c

@@ -277,7 +277,7 @@ proto (int sock, const char *hostname, const char *svc,
     }
     krb5_data_free (&data);
 
-    return(strcmp(message, "ok"));
+    return strcmp(message, "ok") != 0;
 }
 
 static int