Support using the system rapidjson to build

We have a bundled copy of rapidjson in runtime, but some Linux
distributions also ship with another version of that library. Support
using that too, optionally.

This does not change the default behaviour - the bundled copy of
rapidjson is used. A cmake argument of
CLR_CMAKE_USE_SYSTEM_RAPIDJSON=true needs to be set to use the system
version of rapidjson.

Author: omajid

src/native/corehost/CMakeLists.txt

@@ -19,6 +19,10 @@ elseif (CMAKE_CXX_COMPILER_ID MATCHES GNU)
     add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fno-use-cxa-atexit>)
 endif()
 
+if ((NOT DEFINED CLR_CMAKE_USE_SYSTEM_RAPIDJSON) OR (NOT CLR_CMAKE_USE_SYSTEM_RAPIDJSON))
+    include_directories(${CLR_SRC_NATIVE_DIR}/external/)
+endif()
+
 add_subdirectory(hostcommon)
 add_subdirectory(fxr)
 add_subdirectory(hostpolicy)

src/native/corehost/apphost/static/CMakeLists.txt

@@ -21,6 +21,10 @@ include_directories(../../json)
 include_directories(${CLR_SRC_NATIVE_DIR}/libs/System.IO.Compression.Native)
 include_directories(${CLR_SRC_NATIVE_DIR}/libs/Common)
 
+if ((NOT DEFINED CLR_CMAKE_USE_SYSTEM_RAPIDJSON) OR (NOT CLR_CMAKE_USE_SYSTEM_RAPIDJSON))
+    include_directories(${CLR_SRC_NATIVE_DIR}/external/)
+endif()
+
 set(SOURCES
     ../bundle_marker.cpp
     ./hostfxr_resolver.cpp

src/native/corehost/json_parser.cpp

@@ -10,7 +10,7 @@
 #define RAPIDJSON_ERROR_STRING(x) _X(x)
 
 #include <json_parser.h>
-#include <external/rapidjson/error/en.h>
+#include <rapidjson/error/en.h>
 #include "utils.h"
 #include <cassert>
 #include <cstdint>

src/native/corehost/json_parser.h

@@ -17,8 +17,8 @@
 #endif
 
 #include "pal.h"
-#include <external/rapidjson/document.h>
-#include <external/rapidjson/fwd.h>
+#include <rapidjson/document.h>
+#include <rapidjson/fwd.h>
 #include <vector>
 #include "bundle/info.h"
 

src/native/corehost/runtime_config.cpp

@@ -3,7 +3,7 @@
 
 #include "json_parser.h"
 #include "pal.h"
-#include <external/rapidjson/writer.h>
+#include <rapidjson/writer.h>
 #include "roll_fwd_on_no_candidate_fx_option.h"
 #include "runtime_config.h"
 #include "trace.h"