[interchange] Teach Makefile.PL about where to get VERSION from

commit e4105da0491ba5924518eef97cd0f86744d470b5
Author: David Christensen <[email protected]>
Date:   Thu Nov 2 14:22:46 2017 -0500

    Teach Makefile.PL about where to get VERSION from

 Makefile.PL |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.PL b/Makefile.PL
index 7852705..54973cd 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -705,6 +705,17 @@ EOF
 	# Check for extra needed libraries
 	extra_libs($realdir);
 
+	# if we are building from a git checkout, then set the VERSION based on the
+	# closest git tag, otherwise use the last hard-coded version
+
+	if (-d "./.git") {
+		$X{VERSION} = qx(git describe --tags --dirty);
+		chomp $X{VERSION};
+	}
+	else {
+		$X{VERSION} = $VERSION;
+	}
+
 	mk_initp(\%X);
 	delete $X{RPMBUILDDIR};
     return \%X;