[polly] [CMake] Link polly-isl-test with LLVMSupport (#65424)

Otherwise link may fail if user provided additional library to link with via CMAKE_EXE_LINKER_FLAGS. Concrete example is using custom allocator, LLVMSupport provides needed -lpthread in that case.

Closes: https://github.com/llvm/llvm-project/pull/65424
GitOrigin-RevId: b951239932c735deec633bb53c0efa71912155f1
diff --git a/lib/External/CMakeLists.txt b/lib/External/CMakeLists.txt
index 458925f..1869410 100644
--- a/lib/External/CMakeLists.txt
+++ b/lib/External/CMakeLists.txt
@@ -306,6 +306,7 @@
 
   target_link_libraries(polly-isl-test PRIVATE
     PollyISL
+    LLVMSupport
     )
 
   # ISL requires at least C99 to compile. gcc < 5.0 use -std=gnu89 as default.