i18nlangtag: MSVC: pragma warning: make more specific, remove obsolete

Change-Id: I88e2b2e68fbbc86639db986e8f430a90bd4b94f0
Reviewed-on: https://gerrit.libreoffice.org/48982Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

i18nlangtag/source/isolang/inwnt.cxx

@@ -20,15 +20,9 @@
 
 #include <sal/config.h>
 
-#ifdef _MSC_VER
-#pragma warning(push,1) // disable warnings within system headers
-#endif
 #include <windef.h>
 #include <winbase.h>
 #include <winnls.h>
-#ifdef _MSC_VER
-#pragma warning(pop)
-#endif
 #include <osl/mutex.hxx>
 #include <rtl/instance.hxx>
 #include <i18nlangtag/mslangid.hxx>