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>

programs/pkey/CMakeLists.txt

@@ -1,6 +1,10 @@
-if(MSVC)
+set(libs
+    mbedtls
+)
+
+if(WIN32)
     set(libs ${libs} bcrypt)
-endif()
+endif(WIN32)
 
 set(executables_mbedtls
     dh_client