Add include path for SwiftSyntax

Author: phausler

stdlib/public/Observation/Sources/ObservationMacros/CMakeLists.txt

@@ -20,6 +20,10 @@ set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib/${SWIFT_HOST_LIBRARI
 
 set(CMAKE_MACOSX_RPATH YES)
 
+list(APPEND SWIFT_OBSERVATION_SWIFT_FLAGS
+  "-I"
+  ${CMAKE_BINARY_DIR}/lib/${SWIFT_HOST_LIBRARIES_SUBDIRECTORY})
+
 add_swift_target_library(swiftObservationMacros ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
   ObservableMacro.swift