Use yaml_cpp from OS (RobotLocomotion#7352)

* Use yaml_cpp from Ubuntu Xenial or Homebrew.  This removes the bazel external yaml_cpp and replaces it with system yaml_cpp found via pkg-config.

* Exclude yaml_util.h header from install.

* Add yaml-cpp link flag to installed libdrake.so.  This may only be a temporary measure pending maturity of the pc2cps module.

WORKSPACE

@@ -261,12 +261,10 @@ github_archive(
     build_file = "tools/workspace/tinyobjloader/tinyobjloader.BUILD.bazel",
 )
 
-github_archive(
+pkg_config_package(
     name = "yaml_cpp",
-    repository = "jbeder/yaml-cpp",
-    commit = "85af926ddc5f3c8fb438001743e65ec3a039ceec",
-    sha256 = "907fb42a502e1448a73959f9a648771b070d6d8513f16d74149f775fc56550ef",  # noqa
-    build_file = "tools/workspace/yaml_cpp/yaml_cpp.BUILD.bazel",
+    atleast_version = "0.5.2",
+    modname = "yaml-cpp",
 )
 
 load("//tools/workspace/buildifier:buildifier.bzl", "buildifier_repository")

tools/install/libdrake/BUILD.bazel

@@ -39,6 +39,12 @@ install(
     name = "install",
     targets = ["libdrake.so"],
     guess_hdrs = "WORKSPACE",
+    guess_hdrs_exclude = [
+        # This is private visibility; we don't want to have a yaml dependency
+        # in our published headers.  TODO(jwnimmer-tri) Update the guess_hdrs
+        # logic to exclude non-public headers by default.
+        "drake/systems/controllers/yaml_util.h",
+    ],
     allowed_externals = ["//:LICENSE.TXT"],  # Root for our #include paths.
     deps = [
         ":install_cmake_config",

tools/install/libdrake/drake.cps

@@ -82,11 +82,6 @@
       ],
       "X-CMake-Find-Args": ["CONFIG"]
     },
-    "yaml-cpp": {
-      "Version": "0.5.5",
-      "Hints": ["@prefix@/lib/cmake/yaml-cpp"],
-      "X-CMake-Find-Args": ["CONFIG"]
-    },
     "ZLIB": {
       "Version": "1.2.5",
       "X-CMake-Find-Args": ["MODULE"]
@@ -101,7 +96,11 @@
         "@prefix@/include"
       ],
       "Compile-Features": ["c++14"],
-      "Link-Flags": ["-lnlopt", "-ltinyxml2"],
+      "Link-Flags": [
+        "-lnlopt",
+        "-ltinyxml2",
+        "-lyaml-cpp"
+      ],
       "Link-Requires": [
         "fmt:fmt",
         "SDFormat:sdformat",
@@ -128,8 +127,7 @@
         "protobuf:protobuf",
         "robotlocomotion-lcmtypes:robotlocomotion-lcmtypes-cpp",
         "spdlog:spdlog",
-        "stx:stx",
-        "yaml-cpp:yaml-cpp"
+        "stx:stx"
       ]
     },
     "drake-lcmtypes-cpp": {

tools/workspace/BUILD.bazel

@@ -36,7 +36,6 @@ _DRAKE_EXTERNAL_PACKAGE_INSTALLS = ["@%s//:install" % p for p in [
     "tinydir",
     "tinyobjloader",
     "vtk",
-    "yaml_cpp",
 ]] + ["//tools/workspace/%s:install" % p for p in [
     "gflags",
     "jchart2d",