Merge pull request #1544 from suetfei/fix_json

Fix json directory.

.gitmodules

@@ -33,7 +33,7 @@
 [submodule "third_party/mbedtls"]
 	path = third_party/mbedtls
 	url = https://github.com/ARMmbed/mbedtls
-[submodule "third_party/json"]
-	path = third_party/json
+[submodule "third_party/json/json"]
+	path = third_party/json/json
 	url = https://github.com/nlohmann/json
 	branch = master

Package.swift

@@ -246,23 +246,23 @@ let package = Package(
       name: "json",
       path: "third_party/json",
       exclude:[
-        "LICENSES",
-        "cmake",
-        "docs",
-        "single_include",
-        "tests",
-        "tools",
-        "CITATION.cff",
-        "CMakeLists.txt",
-        "ChangeLog.md",
-        "LICENSE.MIT",
-        "Makefile",
-        "README.md",
-        "meson.build",
-        "nlohmann_json.natvis",
-        "wsjcpp.yml",
+        "json/LICENSES",
+        "json/cmake",
+        "json/docs",
+        "json/single_include",
+        "json/tests",
+        "json/tools",
+        "json/CITATION.cff",
+        "json/CMakeLists.txt",
+        "json/ChangeLog.md",
+        "json/LICENSE.MIT",
+        "json/Makefile",
+        "json/README.md",
+        "json/meson.build",
+        "json/nlohmann_json.natvis",
+        "json/wsjcpp.yml",
       ],
-      publicHeadersPath: "include"
+      publicHeadersPath: "json/include"
     ),
     .target(
       name: "protobuf",