link swift libraries when building test executables

Add hook to enable passing in the location of the swift
runtime libraries so we can include them when building
test executables.  If we don't do this and we built
dispatch as a shared library and enabled swift support
the link step fails.

Author: dgrove-oss

tests/CMakeLists.txt

@@ -39,6 +39,13 @@ if(BSD_OVERLAY_FOUND)
                           ${BSD_OVERLAY_LDFLAGS})
 endif()
 
+if(CMAKE_SWIFT_RUNTIME_LIBDIR)
+  target_link_libraries(bsdtestharness
+                        PRIVATE
+                        -L${CMAKE_SWIFT_RUNTIME_LIBDIR} -lswiftCore -lswiftSwiftOnoneSupport
+                        -Wl,-rpath -Wl,${CMAKE_SWIFT_RUNTIME_LIBDIR})
+endif()
+
 function(add_unit_test name)
   set(options DISABLED_TEST)
   set(single_value_args)
@@ -77,6 +84,12 @@ function(add_unit_test name)
                           PRIVATE
                             ${BSD_OVERLAY_LDFLAGS})
   endif()
+  if(CMAKE_SWIFT_RUNTIME_LIBDIR)
+    target_link_libraries(${name}
+                          PRIVATE
+                          -L${CMAKE_SWIFT_RUNTIME_LIBDIR} -lswiftCore -lswiftSwiftOnoneSupport
+                          -Wl,-rpath -Wl,${CMAKE_SWIFT_RUNTIME_LIBDIR})
+  endif()
   target_link_libraries(${name} PRIVATE bsdtests)
   add_test(NAME ${name}
            COMMAND bsdtestharness $<TARGET_FILE:${name}>)