Run eigen_assert on CI runs.

Change-Id: I1cc7cc592dc561a5d9a1d00b2a5ace5087ebd2db
diff --git a/.bazelrc b/.bazelrc
index c80339f..57f01ea 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -50,6 +50,10 @@
 build:msan --test_env MSAN_SYMBOLIZER_PATH=/usr/bin/llvm-symbolizer-3.6
 build:msan --define have_msan=true
 
+# Sometime, we want to be able to have eigen assertions run so that we can
+# catch potential issues (e.g., accessing invalid indices).
+build:eigen  --copt -UNDEBUG
+
 # Show paths to a few more than just 1 target.
 build --show_result 5
 # Dump the output of the failing test to stdout.