Merge pull request #7598 from apple/hughbe-patch-1

Fix build break

Author: hughbe

cmake/modules/AddSwiftUnittests.cmake

@@ -29,7 +29,7 @@ function(add_swift_unittest test_dirname)
     set(new_libnames)
     foreach(dep ${libnames})
       if("${dep}" MATCHES "^(LLVM|Clang|gtest)" AND NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
-        ist(APPEND new_libnames "${LLVM_LIBRARY_OUTPUT_INTDIR}/lib${dep}.a")
+        list(APPEND new_libnames "${LLVM_LIBRARY_OUTPUT_INTDIR}/lib${dep}.a")
       else()
         list(APPEND new_libnames "${dep}")
       endif()