stdlib: build the embedded stdlib core with -enable-ossa-modules

As it is the case for the regular stdlib core

Author: eeckstein

stdlib/public/core/CMakeLists.txt

@@ -414,6 +414,7 @@ if(SWIFT_SHOULD_BUILD_EMBEDDED_STDLIB)
       GYB_SOURCES ${SWIFTLIB_EMBEDDED_GYB_SOURCES}
       SWIFT_COMPILE_FLAGS
         ${swift_stdlib_compile_flags} -Xcc -D__MACH__ -Xcc -D__APPLE__ -Xcc -ffreestanding -enable-experimental-feature Embedded
+        -Xfrontend -enable-ossa-modules
       MODULE_DIR "${CMAKE_BINARY_DIR}/lib/swift/embedded"
       SDK "embedded"
       ARCHITECTURE "${arch}"