Fix developer build with clang-cl failing due exception spec

Clang does seem to understand  __declspec(nothrow) as
used by the COM macros like STDMETHOD. Suppress the warning,
fixing errors like:

qwindowsfontenginedirectwrite.cpp(105,24): error: 'AddBeziers' is missing exception specification '__attribute__((nothrow))' [-Werror,-Wmicrosoft-exception-spec]

Task-number: QTBUG-63512
Change-Id: If582cb0c12c62a7d12c4ae702747aac1f735db3c
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

src/platformsupport/fontdatabases/windows/qwindowsfontenginedirectwrite.cpp

@@ -62,6 +62,9 @@
 
 QT_BEGIN_NAMESPACE
 
+// Clang does not consider __declspec(nothrow) as nothrow
+QT_WARNING_DISABLE_CLANG("-Wmicrosoft-exception-spec")
+
 // Convert from design units to logical pixels
 #define DESIGN_TO_LOGICAL(DESIGN_UNIT_VALUE) \
     QFixed::fromReal((qreal(DESIGN_UNIT_VALUE) / qreal(m_unitsPerEm)) * fontDef.pixelSize)

src/plugins/platforms/windows/qwindowscombase.h

@@ -107,6 +107,9 @@ private:
     ULONG m_ref;
 };
 
+// Clang does not consider __declspec(nothrow) as nothrow
+QT_WARNING_DISABLE_CLANG("-Wmicrosoft-exception-spec")
+
 QT_END_NAMESPACE
 
 #endif // QWINDOWSCOMBASE_H