Correct check for WIN32 in cmake files for programs

Condition was checking for Visual Studio, not use of WIN32

Signed-off-by: Simon Butcher <simon.butcher@arm.com>
diff --git a/programs/ssl/CMakeLists.txt b/programs/ssl/CMakeLists.txt
index 9871952..cfa9a0f 100644
--- a/programs/ssl/CMakeLists.txt
+++ b/programs/ssl/CMakeLists.txt
@@ -5,9 +5,9 @@
     ${mbedtls_target}
 )
 
-if(MSVC)
+if(WIN32)
     set(libs ${libs} bcrypt)
-endif()
+endif(WIN32)
 
 set(executables
     dtls_client