updated build system

ax_init_standard_project.m4

@@ -265,14 +265,8 @@ maintainer-clean-cxx-targets:
 EOF
 ])
 
-# use this in configure.ac to support CppUnit for C++ unit tests
-AC_DEFUN([AX_USE_CPPUNIT], [
-  AM_PATH_CPPUNIT([1.0.0], [have_cppunit="yes"], [have_cppunit="no"])
-  # infos and warnings
-  if test "$have_cppunit" = "no"; then
-    AC_MSG_WARN([Missing cppunit development library!
-     - you cannot check the library using "make check"
-     - everything else works perfectly]); fi
+# use this in configure.ac to support tests without CppUnit
+AC_DEFUN([AX_BUILD_TEST], [
   AC_CONFIG_FILES([test/makefile])
   AX_ADD_MAKEFILE_TARGET_DEP([maintainer-clean-am], [maintainer-clean-test-targets], [test/makefile.in])
   test -f test/makefile.in && cat >> test/makefile.in <<EOF
@@ -283,6 +277,17 @@ maintainer-clean-test-targets:
 EOF
 ])
 
+# use this in configure.ac to support CppUnit for C++ unit tests
+AC_DEFUN([AX_USE_CPPUNIT], [
+  AM_PATH_CPPUNIT([1.0.0], [have_cppunit="yes"], [have_cppunit="no"])
+  # infos and warnings
+  if test "$have_cppunit" = "no"; then
+    AC_MSG_WARN([Missing cppunit development library!
+     - you cannot check the project using "make check"
+     - everything else works perfectly]); fi
+  AX_BUILD_TEST
+])
+
 # use this in configure.ac to support C++ examples
 AC_DEFUN([AX_BUILD_EXAMPLES], [
   AC_CONFIG_FILES([examples/makefile])
@@ -696,3 +701,15 @@ AC_DEFUN([AX_CHECK_VALID_LD_FLAG], [
   AC_SUBST(LDFLAGS)
   AC_MSG_RESULT([$newflag in $LDFLAGS])
 ])
+
+# Check if a package exists in the current distribution, if yes, require it
+# in debian/control.in append @DEB_DEPEND_IFEXISTS@ to Build-Depends
+#  - parameter:
+#     $1 = package name
+AC_DEFUN([AX_DEB_DEPEND_IFEXISTS], [
+  pkg=$1
+  if test -n "$(apt-cache policy -q ${pkg} 2> /dev/null)"; then
+     DEB_DEPEND_IFEXISTS+=", ${pkg}"
+  fi
+  AC_SUBST(DEB_DEPEND_IFEXISTS)
+])