https://lists.fedoraproject.org/pipermail/scm-commits/Week-of-Mon-20150216/1511118.html

--- vxl-git4e07960/vcl/vcl_compiler.h~	2012-11-02 12:08:21.000000000 +0100
+++ vxl-git4e07960/vcl/vcl_compiler.h	2015-02-15 13:50:46.376329878 +0100
@@ -119,6 +119,10 @@
 #  else
 #   define VCL_GCC_40
 #  endif
+# elif (__GNUC__== 5)
+// pretend GCC 5 to be GCC 4
+#  define VCL_GCC_4
+#  define VCL_GCC_41
 # else
 #  error "Dunno about this gcc"
 # endif