minor optimizations
[util-vserver.git] / util-vserver / m4 / ensc_kerneldir.m4
index d4a2bdc..8555e67 100644 (file)
@@ -50,6 +50,8 @@ AC_DEFUN([ENSC_KERNEL_HEADERS],
                ensc_cv_path_kernelheaders=$ensc_cv_path_kerneldir/include
        ])
 
-       $1=$ensc_cv_path_kernelheaders
-       AC_SUBST($1)
+       if test x"$1" != x; then
+               $1=$ensc_cv_path_kernelheaders
+               AC_SUBST($1)
+       fi
 ])