[master] 05f8503 fix out-of-tree builds / distcheck

[Nils Goroll]

commit 05f850387eefde7d2dc8f917e8c366c16d76df38
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Tue Mar 6 16:34:06 2018 +0100

    fix out-of-tree builds / distcheck

diff --git a/include/Makefile.am b/include/Makefile.am
index 0831e2e..d0d88c9 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -125,8 +125,8 @@ GENERATED_H = vcl.h $(GEN_H)
 
 vcs_version.h:
 	@if test -e $(top_srcdir)/.git || \
-	  ! test -f vmod_abi.h || \
-	  ! test -f vcs_version.h ; then \
+	  ! test -f $(srcdir)/vmod_abi.h || \
+	  ! test -f $(srcdir)/vcs_version.h ; then \
 	    @PYTHON@ $(srcdir)/generate.py \
 		$(top_srcdir) $(top_builddir) ; \
 	fi