adding clrgc variant with regions enabled (dotnet#89129)

* adding clrgc variant with regions enabled

* only build regions for 64 bit platforms

* rename to clrgcexp for experimental

src/coreclr/gc/CMakeLists.txt

@@ -104,6 +104,16 @@ list(APPEND GC_SOURCES ${GC_HEADERS})
 
 convert_to_absolute_path(GC_SOURCES ${GC_SOURCES})
 
+# clrgcexp is build with standalone+regions
+if (CLR_CMAKE_TARGET_ARCH_ARM64 OR CLR_CMAKE_TARGET_ARCH_AMD64)
+  add_library_clr(clrgcexp SHARED ${GC_SOURCES})
+  add_dependencies(clrgcexp eventing_headers)
+  target_link_libraries(clrgcexp PRIVATE ${GC_LINK_LIBRARIES})
+  target_compile_definitions(clrgcexp PRIVATE -DUSE_REGIONS)
+  install_clr(TARGETS clrgcexp DESTINATIONS . COMPONENT runtime)
+endif (CLR_CMAKE_TARGET_ARCH_ARM64 OR CLR_CMAKE_TARGET_ARCH_AMD64)
+
+# clrgc is build with standalone+segments
 add_library_clr(clrgc SHARED ${GC_SOURCES})
 add_dependencies(clrgc eventing_headers)
 target_link_libraries(clrgc PRIVATE ${GC_LINK_LIBRARIES})