Quiet down the fortran some more.

Change-Id: I4d30dc0125e26dc9c7bf1b9d7809be321d4b5974
diff --git a/tools/build_rules/fortran.bzl b/tools/build_rules/fortran.bzl
index 635e7d7..ed586f7 100644
--- a/tools/build_rules/fortran.bzl
+++ b/tools/build_rules/fortran.bzl
@@ -3,7 +3,7 @@
       ctx.fragments.cpp.c_options +
       ctx.fragments.cpp.unfiltered_compiler_options([]) +
       ['-fPIC', '-Wno-maybe-uninitialized', '-Wno-unused-dummy-argument',
-       '-Wno-conversion', '-Wno-unused-variable'])
+       '-Wno-conversion', '-Wno-unused-variable', '-Wno-character-truncation'])
 
   cmd = toolchain_cflags + ['-c', ctx.file.src.path, '-o', ctx.outputs.pic_o.path]
   filtered_cmd = []