Add some protection against PMIx v4

Ensure we can build against PMIx v3.1.5

Fixes #8089

Signed-off-by: Ralph Castain <rhc@pmix.org>

ompi/dpm/dpm.c

@@ -696,7 +696,11 @@ static int dpm_convert(opal_list_t *infos,
                 /* does it conflict? */
                if (0 != strncasecmp(ck, directive, strlen(directive))) {
                     opal_asprintf(&help_str, "Conflicting directives \"%s %s\"", ck, directive);
+#if PMIX_NUMERIC_VERSION >= 0x00040000
                     attr = PMIx_Get_attribute_string(option);
+#else
+                    attr = option;
+#endif
                     opal_show_help("help-dpm.txt", "deprecated-fail", true,
                                    infokey, attr, help_str);
                     free(help_str);
@@ -723,7 +727,11 @@ static int dpm_convert(opal_list_t *infos,
                     if (OMPI_SUCCESS != rc) {
                         /* we have a conflict */
                         opal_asprintf(&ptr, "  Option %s\n  Conflicting modifiers \"%s %s\"", option, infokey, modifier);
+#if PMIX_NUMERIC_VERSION >= 0x00040000
                         attr = PMIx_Get_attribute_string(option);
+#else
+                        attr = option;
+#endif
                         opal_show_help("help-dpm.txt", "deprecated-fail", true,
                                        infokey, attr, ptr);
                         free(ptr);

ompi/runtime/ompi_rte.c

@@ -668,6 +668,7 @@ int ompi_rte_init(int *pargc, char ***pargv)
         }
     }
 
+#ifdef PMIX_APP_ARGV
     /* get our command - defaults to our appnum */
     ev1 = NULL;
     OPAL_MODEX_RECV_VALUE_OPTIONAL(rc, PMIX_APP_ARGV,
@@ -681,13 +682,21 @@ int ompi_rte_init(int *pargc, char ***pargv)
             opal_process_info.command = opal_argv_join(tmp, ' ');
         }
     }
+#else
+    tmp = *pargv;
+    if (NULL != tmp) {
+        opal_process_info.command = opal_argv_join(tmp, ' ');
+    }
+#endif
 
+#ifdef PMIX_REINCARNATION
     /* get our reincarnation number */
     OPAL_MODEX_RECV_VALUE_OPTIONAL(rc, PMIX_REINCARNATION,
                                    &OPAL_PROC_MY_NAME, &u32ptr, PMIX_UINT32);
     if (PMIX_SUCCESS == rc) {
         opal_process_info.reincarnation = u32;
     }
+#endif
 
     /* get the number of local peers - required for wireup of
      * shared memory BTL, defaults to local node */