build: Import and use external Autoconf repo

Start using our external repo of Autoconf macros shared across
the Open MPI, OpenPMIx, and PRRTE projects. For now, only
move OAC_ASSERT_LITERAL and  OAC_CHECK_PACKAGE, plus their
dependencies, but we expect to move more over time. This will
help manage the divergence in macros between the three
projects (we already had significant divergence in CHECK_PACKAGE
after less than a year).

Signed-off-by: Brian Barrett <[email protected]>

Author: bwbarrett

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "oac"]
+	path = config/oac
+	url = ../../open-mpi/oac

autogen.pl

@@ -887,6 +887,52 @@ sub replace_config_sub_guess {
 
 #---------------------------------------------------------------------------
 
+++$step;
+verbose "\n$step. Checking for git submodules\n\n";
+
+# Make sure we got a submodule-full clone.  If not, abort and let a
+# human figure it out.
+if (-f ".gitmodules") {
+    open(IN, "git submodule status|")
+        || die "Can't run \"git submodule status\"";
+    while (<IN>) {
+        chomp;
+        $_ =~ m/^(.)(.{40}) ([^ ]+) *\(*([^\(\)]*)\)*$/;
+        my $status     = $1;
+        my $local_hash = $2;
+        my $path       = $3;
+        my $extra      = $4;
+
+        # Make sure the submodule is there
+        if ($status eq "-") {
+            print("    ==> ERROR: Missing
+
+The submodule \"$path\" is missing.
+
+Perhaps you forgot to \"git clone --recursive ...\", or you need to
+\"git submodule update --init --recursive\"...?\n\n");
+            exit(1);
+        }
+
+        # See if the submodule is at the expected git hash
+        # (it may be ok if it's not -- just warn the user)
+        $extra =~ m/-g(.+)/;
+        my $remote_hash = $1;
+        if ($remote_hash) {
+            my $abbrev_local_hash = substr($local_hash, 0, length($remote_hash));
+            if ($remote_hash ne $abbrev_local_hash) {
+                print("    ==> WARNING: Submodule hash is different than upstream.
+         If this is not intentional, you may want to run:
+         \"git submodule update --init --recursive\"\n");
+            } else {
+                print("    Local hash == remote hash (good!)\n");
+            }
+        }
+    }
+}
+
+#---------------------------------------------------------------------------
+
 # No platform file -- write an empty list
 $m4 .= "m4_define([autogen_platform_file], [])\n\n";
 
@@ -973,7 +1019,7 @@ sub replace_config_sub_guess {
 
 # Run autoreconf
 verbose "==> Running autoreconf\n";
-my $cmd = "autoreconf -ivf --warnings=all,no-obsolete,no-override -I config";
+my $cmd = "autoreconf -ivf --warnings=all,no-obsolete,no-override -I config -I config/oac";
 safe_system($cmd);
 
 patch_autotools_output(".");