[internal_sdk] Include rapidjson

... a transitive dependency of debug_agent

Bug: 112028
Change-Id: I2578523f649ea76ca34d053d1c5a8f3fd72ddd40
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/rapidjson/+/766563
Reviewed-by: Shai Barack <shayba@google.com>
Commit-Queue: Jay Zhuang <jayzhuang@google.com>

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index 4de322e..123249d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -25,11 +25,10 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+import("//build/cpp/sdk_source_set.gni")
+
 config("rapidjson_config") {
-  include_dirs = [
-    ".",
-    "include",
-  ]
+  include_dirs = [ "include" ]
 
   # rapidjson needs these defines to support C++11 features. These features
   # are intentionally not autodetected by rapidjson.
@@ -44,7 +43,10 @@
   cflags = [ "-Wno-ambiguous-reversed-operator" ]
 }
 
-source_set("rapidjson") {
+sdk_source_set("rapidjson") {
+  category = "internal"
+  include_base = "include"
+
   sources = [
     "include/rapidjson/allocators.h",
     "include/rapidjson/cursorstreamwrapper.h",