[AVR] Allow setting up the integrated test suite as an external project

[dylanmckay]

Summary

This allows the AVR integrated test suite to be set up and configured
with LLVM.

CMakeLists.txt

 
 add_subdirectory(runtimes)
 
 if( LLVM_INCLUDE_EXAMPLES )
   add_subdirectory(examples)
 endif()
 
 if( LLVM_INCLUDE_TESTS )
-  if(EXISTS ${LLVM_MAIN_SRC_DIR}/projects/test-suite AND TARGET clang)
-    include(LLVMExternalProjectUtils)
-    llvm_ExternalProject_Add(test-suite ${LLVM_MAIN_SRC_DIR}/projects/test-suite
-      USE_TOOLCHAIN
-      EXCLUDE_FROM_ALL
-      NO_INSTALL
-      ALWAYS_CLEAN)
+
+  if(EXISTS ${LLVM_MAIN_SRC_DIR}/projects/test-suite AND TARGET clang)
+    llvm_ExternalProject_AddTestSuite(test-suite ${LLVM_MAIN_SRC_DIR}/projects/test-suite)
   endif()
+
+  if(EXISTS ${LLVM_MAIN_SRC_DIR}/projects/avr-metal AND ${LLVM_TARGETS_TO_BUILD} MATCHES "AVR")
+    llvm_ExternalProject_AddTestSuite(avr-metal ${LLVM_MAIN_SRC_DIR}/projects/avr-metal)
+  endif()
+
   add_subdirectory(test)
   add_subdirectory(unittests)
   if (MSVC)
     # This utility is used to prevent crashing tests from calling Dr. Watson on
     # Windows.
     add_subdirectory(utils/KillTheDoctor)
   endif()
 

cmake/modules/LLVMExternalProjectUtils.cmake

foreach(target ${ARG_EXTRA_TARGETS})
     add_custom_target(${target}
       COMMAND ${build_runtime_cmd}
       DEPENDS ${name}-configure
       WORKING_DIRECTORY ${BINARY_DIR}
       VERBATIM
       USES_TERMINAL)
   endforeach()
 endfunction()
+
+# Adds an external project which has nothing to install and
+# is not built by default.
+function(llvm_ExternalProject_AddTestSuite name source_dir)
+  llvm_ExternalProject_Add(${name} ${source_dir}
+    USE_TOOLCHAIN EXCLUDE_FROM_ALL NO_INSTALL ALWAYS_CLEAN)
+endfunction()