gtsam-bazel:用bazel构建gtsam

# gtsam-bazel Build gtsam with bazel, tested on Manjaro ## Test Run official [ISAM2](https://github.com/borglab/gtsam/blob/develop/examples/VisualISAM2Example.cpp) example with ``` bazel run @com_github_borglab_gtsam//:visual-isam2-example ``` ## Usage Add `@com_github_borglab_gtsam//:libgtsam` to `cc_binary` or `cc_library` dependency For example: ``` cc_binary( name = "gtsam-demo", srcs = ["gtsam-demo.cc"], deps = [ "@com_github_borglab_gtsam//:libgtsam", ], ) ```