build-sys: remove vala generated sources only when valac is around

Makefile.am

@@ -335,9 +335,6 @@ units/session/%: units/%.m4 Makefile
 	$(M4_PROCESS_SESSION)
 
 CLEANFILES = \
-	src/systemd-interfaces.c \
-	src/systemctl.c \
-	src/systemadm.c \
 	units/systemd-initctl.service \
 	units/systemd-logger.service \
 	units/syslog.target \
@@ -350,6 +347,13 @@ CLEANFILES = \
 	man/systemd.special.7 \
 	man/systemd.special.html
 
+if HAVE_VALAC
+CLEANFILES += \
+	src/systemd-interfaces.c \
+	src/systemctl.c \
+	src/systemadm.c
+endif
+
 if HAVE_XSLTPROC
 XSLTPROC_PROCESS_MAN = \
 	$(AM_V_GEN)$(MKDIR_P) $(dir $@) && \

README

@@ -27,7 +27,7 @@ AUTHOR:
         Lennart Poettering with major support from Kay Sievers
 
 REQUIREMENTS:
-        Linux kernel >= 2.6.30 (with autofs4, devtmpfs and the debug cgroup controller)
+        Linux kernel >= 2.6.30 (with autofs4, devtmpfs, cgroups)
         libudev >= 151
         libcgroup >= 0.35
         vala >= 0.80

configure.ac

@@ -123,6 +123,7 @@ AM_CONDITIONAL(HAVE_GTK, [test "$have_gtk" = "yes"])
 
 AM_PROG_VALAC([0.8])
 AC_SUBST(VAPIDIR)
+AM_CONDITIONAL(HAVE_VALAC, test x"$VALAC" != x)
 
 AC_PATH_PROG([XSLTPROC], [xsltproc])
 AM_CONDITIONAL(HAVE_XSLTPROC, test x"$XSLTPROC" != x)