cmake SWIFT_STDLIB_HAS_DLSYM examples

swiftlang/swift cmake/modules/AddSwiftUnittests.cmake :81 

target_compile_definitions("${test_dirname}" PRIVATE
      "SWIFT_STDLIB_HAS_DLSYM=1")

swiftlang/swift cmake/modules/AddSwiftUnittests.cmake :84 

target_compile_definitions("${test_dirname}" PRIVATE
      "SWIFT_STDLIB_HAS_DLSYM=0")

swiftlang/swift stdlib/cmake/modules/StdlibOptions.cmake :152 

option(SWIFT_STDLIB_HAS_DLSYM
       "Build stdlib assuming the runtime environment provides the dlsym API."
       TRUE)