Link error when use as static library on windows. (#1470)

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1a6f073..55402e6 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -55,7 +55,7 @@
 endif()
 
 if (NOT BUILD_SHARED_LIBS)
-  target_compile_definitions(benchmark PRIVATE -DBENCHMARK_STATIC_DEFINE)
+  target_compile_definitions(benchmark PUBLIC -DBENCHMARK_STATIC_DEFINE)
 endif()
 
 # Benchmark main library