butc: Fix problems found by static analysis

Several static analysis tools have identified various problems:
 - use of uninitlized variables                   (scan-build)
 - missing checks to ensure *alloc was successful (infer)
 - possible memory leaks                          (scan-build, cppcheck)

To resolve the above problems:
 - ensure variables are initialized to safe defaults
 - add checks to ensure *alloc was successful before using the memory
 - fix possible memory leaks by freeing memory

This commit is a reorganization of commits developed by Pat Riehecky,
who ran the static analysis tools and developed the fixes.

Change-Id: Ic5e222e344df4d5a3e317fcbb2f30a09dce93793
Reviewed-on: https://gerrit.openafs.org/14679
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>

src/butc/list.c

@@ -9,6 +9,7 @@
 
 #include <afsconfig.h>
 #include <afs/param.h>
+#include <afs/opr.h>
 
 #include <roken.h>
 
@@ -61,6 +62,7 @@ CreateNode(struct dumpNode **newNode)
 {
     /* get space */
     *newNode = calloc(1, sizeof(struct dumpNode));
+    opr_Assert(*newNode != NULL);
 
     (*newNode)->next = dumpQHeader->next;
     dumpQHeader->next = *newNode;

src/butc/recoverDb.c

@@ -163,7 +163,7 @@ scanVolData(afs_int32 taskId, struct butm_tapeInfo *curTapePtr,
     char *buffer[2];
     int hasdata[2], curr, prev;
     afs_uint32 chunkSize = 0;
-    afs_int32 nbytes;
+    afs_int32 nbytes = 0;
     afs_int32 code = 0;
     afs_int32 rcode, tcode;