MSVC: Fix the CET parameters

To enable CET for MSVC, only passing "/CETCOMPAT" to
the linker should be sufficient.

Enabling generation of EH Continuation (EHCONT) metadata
is additional protection and should not be necessary.
It also requires all the dependencies to be re-compiled
with EHCONT enabled, otherwise the linker will refuse
to link the obj files. However, this is rather hard
to achieve if your application depends on many 3rd-party
libraries, so to let people enable CET more freely,
we don't enable EHCONT guard by default.

Pick-to: 6.4
Change-Id: Iba08a5ec56c474d291991fb751a0de764719bd85
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

cmake/QtInternalTargets.cmake

@@ -272,11 +272,8 @@ endif()
 
 if(QT_FEATURE_intelcet)
     if(MSVC)
-        target_compile_options(PlatformCommonInternal INTERFACE
-            -guard:ehcont
-        )
         target_link_options(PlatformCommonInternal INTERFACE
-            -guard:ehcont -CETCOMPAT
+            -CETCOMPAT
         )
     else()
         target_compile_options(PlatformCommonInternal INTERFACE