[Local GC] Implement loader protocol for a standalone GC (#14663)

* First cut of the load protocol

* Implement for non-standalone GC

* Initial working implementation

* First steps towards not using GetProcAddress when not using a standalone GC

* Factor out loading routines into standalone and non-standalone cases

* Remove the FEATURE_STANDALONE_GC_ONLY build

* Code cleanup and comments

* Comments for the version numbers

* Use more appropriate type for config string

* add GC_LOAD_STATUS_BEFORE_START to disambiguate failures before the start of the load and failures at the beginning of the load

* FEATURE_STANDALONE_GC on by default

* Implement YieldProcessor and MemoryBarrier for arm and arm64

* Remove missed FEATURE_STANDALONE_GC feature check

2 files changed, 5 insertions, 2 deletions

diff --git a/src/gc/sample/CMakeLists.txt b/src/gc/sample/CMakeLists.txt
index 42f097a6e3..6f8aa615d7 100644
--- a/src/gc/sample/CMakeLists.txt
+++ b/src/gc/sample/CMakeLists.txt
@@ -5,6 +5,8 @@ set(CMAKE_INCLUDE_CURRENT_DIR ON)
 include_directories(..)
 include_directories(../env)
 
+add_definitions(-DFEATURE_REDHAWK)
+
 set(SOURCES
     GCSample.cpp
     gcenv.ee.cpp
@@ -14,6 +16,7 @@ set(SOURCES
     ../gchandletable.cpp
     ../gcscan.cpp
     ../gcwks.cpp
+    ../gcload.cpp
     ../handletable.cpp
     ../handletablecache.cpp
     ../handletablecore.cpp
diff --git a/src/gc/sample/GCSample.cpp b/src/gc/sample/GCSample.cpp
index 62eec6698f..4248d92256 100644
--- a/src/gc/sample/GCSample.cpp
+++ b/src/gc/sample/GCSample.cpp
@@ -107,7 +107,7 @@ void WriteBarrier(Object ** dst, Object * ref)
     ErectWriteBarrier(dst, ref);
 }
 
-extern "C" bool InitializeGarbageCollector(IGCToCLR* clrToGC, IGCHeap** gcHeap, IGCHandleManager** gcHandleManager, GcDacVars* gcDacVars);
+extern "C" HRESULT GC_Initialize(IGCToCLR* clrToGC, IGCHeap** gcHeap, IGCHandleManager** gcHandleManager, GcDacVars* gcDacVars);
 
 int __cdecl main(int argc, char* argv[])
 {
@@ -133,7 +133,7 @@ int __cdecl main(int argc, char* argv[])
     GcDacVars dacVars;
     IGCHeap *pGCHeap;
     IGCHandleManager *pGCHandleManager;
-    if (!InitializeGarbageCollector(nullptr, &pGCHeap, &pGCHandleManager, &dacVars))
+    if (GC_Initialize(nullptr, &pGCHeap, &pGCHandleManager, &dacVars) != S_OK)
     {
         return -1;
     }