GN: Add BUILD.gn file to third_party/jsoncpp

build/config/linux/BUILD.gn

Index: build/config/linux/BUILD.gn
diff --git a/build/config/linux/BUILD.gn b/build/config/linux/BUILD.gn
index 7241ad6b29be0259651a029deae099fa6ece2dc9..a79748ac5016ad695a2112ec126e2e07d3b9cdb4 100644
--- a/build/config/linux/BUILD.gn
+++ b/build/config/linux/BUILD.gn
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/crypto.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/sysroot.gni")
 
@@ -52,6 +53,34 @@ pkg_config("dbus") {
   packages = [ "dbus-1" ]
 }
 
+config("no_openssl_config") {
+  # TODO(kjellander): Find out how to convert GYP include_dirs+ (i.e. insert
+  # first in the include path?).
+  include_dirs = [ "//net/third_party/nss/ssl" ]
+
+  configs = [ "//third_party/nss:system_nss_no_ssl_config" ]
+}
+
+config("ssl") {
+  if (use_openssl) {
+    deps = [ "//third_party/openssl" ]
+  } else {
+    deps = [ "//net/third_party/nss/ssl:libssl" ]
+
+    direct_dependent_configs = [
+      ":ssl_include_config",
+    ]
+
+    if (is_clang) {
+      cflags += [
+        # There is a broken header guard in /usr/include/nss/secmod.h:
+        # https://bugzilla.mozilla.org/show_bug.cgi?id=884072
+        "-Wno-header-guard",
+      ]
+    }
+  }
+}
+
 config("x11") {
   # Don't bother running pkg-config for these X related libraries since it just
   # returns the same libs, and forking pkg-config is slow.