opal/util: fix simple compiler warnings

Note that free(NULL) is legal in C99, so remove the
"__opal_attribute_nonnull__(1)" attribute from the buffer param to
opal_free() debug wrapper.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

Author: jsquyres

opal/util/malloc.h

@@ -12,6 +12,7 @@
  *                         All rights reserved.
  * Copyright (c) 2018      Triad National Security, LLC. All rights
  *                         reserved.
+ * Copyright (c) 2022      Cisco Systems, Inc.  All rights reserved
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -127,7 +128,7 @@ OPAL_DECLSPEC void *opal_realloc(void *ptr, size_t size, const char *file, int l
  * to configure (or by default if you're building in a SVN
  * checkout).
  */
-OPAL_DECLSPEC void opal_free(void *addr, const char *file, int line) __opal_attribute_nonnull__(1);
+OPAL_DECLSPEC void opal_free(void *addr, const char *file, int line);
 
 /**
  * Used to set the debug level for malloc debug.

opal/util/stacktrace.c

@@ -10,7 +10,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2006      Sun Microsystems, Inc.  All rights reserved.
- * Copyright (c) 2008-2009 Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2008-2022 Cisco Systems, Inc.  All rights reserved
  * Copyright (c) 2017      IBM Corporation.  All rights reserved.
  * Copyright (c) 2017      FUJITSU LIMITED.  All rights reserved.
  * Copyright (c) 2019      Triad National Security, LLC. All rights
@@ -640,7 +640,6 @@ int opal_util_register_stackhandlers(void)
         set_stacktrace_filename();
         opal_stacktrace_output_fileno = -1;
     } else if (0 == strncasecmp(opal_stacktrace_output_filename, "file:", 5)) {
-        char *filename_cpy = NULL;
         next = strchr(opal_stacktrace_output_filename, ':');
         next++; // move past the ':' to the filename specified
 
@@ -654,8 +653,6 @@ int opal_util_register_stackhandlers(void)
             sizeof(char) * opal_stacktrace_output_filename_max_len);
         set_stacktrace_filename();
         opal_stacktrace_output_fileno = -1;
-
-        free(filename_cpy);
     } else {
         opal_stacktrace_output_fileno = fileno(stderr);
     }