Fix warnings

Warnings came up using MinGW 4.4:
* botan.cpp: integer constant is too large for 'long' type
* dnssd_clientlib.c, dnssd_clientstub.c: ignoring #pragma warning
* hostutils.cpp: comparison between signed and unsigned integer expressions
* qmakebuildins.cpp: 'QString windowsErrorCode()' defined but not used

Change-Id: I80827f7f740ff380f13cef96d6b43baaa7e179cb
Reviewed-by: Christian Kandeler <christian.kandeler@nokia.com>
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/shared/hostutils.cpp

@@ -206,7 +206,7 @@ void formatWindowsException(unsigned long code, quint64 address,
     str.setIntegerBase(10);
 }
 
-bool isDebuggerWinException(long code)
+bool isDebuggerWinException(unsigned long code)
 {
     return code == EXCEPTION_BREAKPOINT || code == EXCEPTION_SINGLE_STEP;
 }