Don't build dlopen when building for Windows

Windows doesn't have dlopen, not even Linux emulation environments such as
MinGW.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/test/CMakeLists.txt b/programs/test/CMakeLists.txt
index 3a8affb..1a79e97 100644
--- a/programs/test/CMakeLists.txt
+++ b/programs/test/CMakeLists.txt
@@ -27,7 +27,8 @@
     target_link_libraries(cpp_dummy_build ${mbedcrypto_target})
 endif()
 
-if(USE_SHARED_MBEDTLS_LIBRARY)
+if(USE_SHARED_MBEDTLS_LIBRARY AND
+   NOT ${CMAKE_SYSTEM_NAME} MATCHES "[Ww][Ii][Nn]")
     add_executable(dlopen "dlopen.c")
     target_include_directories(dlopen PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../../include)
     if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")