fix rand_r check in CMakeLists
@@ -101,7 +101,7 @@ else ()
set(BSON_HAVE_GMTIME_R 1)
endif ()
-CHECK_FUNCTION_EXISTS(rand_r stdlib.h BSON_HAVE_RAND_R)
+CHECK_FUNCTION_EXISTS(rand_r BSON_HAVE_RAND_R)
if (NOT BSON_HAVE_RAND_R)
set(BSON_HAVE_RAND_R 0)
else ()
