Upgrade to a new Bazel version

This one has better performance and various new features. It also
prevents us from falling too far behind upstream.

Change-Id: I3b8e1c5bda886ea2e990523af9e6de2434c784be
diff --git a/tools/build_rules/fortran.bzl b/tools/build_rules/fortran.bzl
index f8d0add..2d6e4db 100644
--- a/tools/build_rules/fortran.bzl
+++ b/tools/build_rules/fortran.bzl
@@ -36,11 +36,11 @@
     progress_message = 'Building %s' % ctx.outputs.pic_o.short_path,
   )
 
-def _define_fortran_output(attrs):
-  if not attrs.src.name.endswith('.f'):
+def _define_fortran_output(src):
+  if not src.name.endswith('.f'):
     fail('Fortran files must end in \'.f\'', 'src')
 
-  fortran_file_base = attrs.src.name[:-2]
+  fortran_file_base = src.name[:-2]
   return {
     'pic_o': fortran_file_base + '.pic.o',
   }