inetcomm: Fix printing NULL strings.

[Francois Gouget]

---

This fixes a crash that occurred in the conformance tests on my Solaris   
VMs when tracing was turned on.

 dlls/inetcomm/mimeole.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/dlls/inetcomm/mimeole.c b/dlls/inetcomm/mimeole.c
index f297c29..8a1e3d4 100644
--- a/dlls/inetcomm/mimeole.c
+++ b/dlls/inetcomm/mimeole.c
@@ -2134,7 +2134,8 @@ static HRESULT WINAPI MimeMessage_IsContentType(
 {
     HRESULT hr;
     IMimeBody *mime_body;
-    TRACE("(%p)->(%p, %s, %s)\n", iface, hBody, pszPriType, pszSubType);
+    TRACE("(%p)->(%p, %s, %s)\n", iface, hBody, debugstr_a(pszPriType),
+          debugstr_a(pszSubType));
 
     hr = IMimeMessage_BindToObject(iface, hBody, &IID_IMimeBody, (void**)&mime_body);
     if(FAILED(hr)) return hr;
-- 
1.7.5.4