vsh-table: allow empty columns

Trivially implement this by deleting the bogus check in
vshTableSafeEncode.

Now it returns an empty string for an empty string instead
of returning NULL without setting an error.
Signed-off-by: NJán Tomko <jtomko@redhat.com>

tests/vshtabletest.c

@@ -291,7 +291,8 @@ testNTables(const void *opaque ATTRIBUTE_UNUSED)
         " Id   Name       Status\n"
         "--------------------------\n"
         " 1    fedora28   running\n"
-        " 2    rhel7.5    running\n";
+        " 2    rhel7.5    running\n"
+        " 3    gazpacho   \n";
     const char *exp2 =
         " Id   Name   Status\n"
         "---------------------\n";
@@ -311,6 +312,7 @@ testNTables(const void *opaque ATTRIBUTE_UNUSED)
         goto cleanup;
     vshTableRowAppend(table1, "1", "fedora28", "running", NULL);
     vshTableRowAppend(table1, "2", "rhel7.5", "running", NULL);
+    vshTableRowAppend(table1, "3", "gazpacho", "", NULL);
     act1 = vshTablePrintToString(table1, true);
 
     table2 = vshTableNew("Id", "Name", "Status", NULL);

tools/vsh-table.c

@@ -219,9 +219,6 @@ vshTableSafeEncode(const char *s, size_t *width)
 
     memset(&st, 0, sizeof(st));
 
-    if (!sz)
-        return NULL;
-
     if (VIR_ALLOC_N(buf, (sz * HEX_ENCODE_LENGTH) + 1) < 0)
         return NULL;