Merge pull request swiftlang#529 from compnerd/definition-handling

build: repair macro definition handling

Author: ktopley-apple

src/CMakeLists.txt

@@ -109,12 +109,12 @@ if(CMAKE_SYSTEM_NAME STREQUAL Windows)
  _CRT_NONSTDC_NO_WARNINGS
  _CRT_SECURE_NO_WARNINGS)
 elseif(CMAKE_SYSTEM_NAME STREQUAL Android)
- target_compile_definitions(dispatch PRIVATE
+ target_compile_options(dispatch PRIVATE
  -U_GNU_SOURCE)
 endif()
 if(DISPATCH_ENABLE_ASSERTS)
  target_compile_definitions(dispatch PRIVATE
- -DDISPATCH_DEBUG=1)
+ DISPATCH_DEBUG=1)
 endif()
 
 if("${CMAKE_C_SIMULATE_ID}" STREQUAL "MSVC")