Silence a warning about unrecognised pragma with ICC

src/libs/cplusplus/MatchingText.cpp(64): warning #161: unrecognized #pragma
  #    pragma GCC diagnostic ignored "-Wstrict-overflow"
              ^

This pragma is recognised in GCC only, so don't enable it for when ICC
fakes to be GCC.

Change-Id: I3d9830dc2b12632dd08d8c8961219bd253ad8c1d
Reviewed-by: hjk <qthjk@ovi.com>

src/libs/cplusplus/MatchingText.cpp

@@ -60,7 +60,7 @@ static bool shouldOverrideChar(QChar ch)
 //   qstring.h:1175:39: warning: assuming signed overflow does not occur when assuming that (X - c) > X is always false
 //
 // caused by Q_ASSERT in QStringRef::at()
-#ifdef Q_CC_GNU
+#if defined(Q_CC_GNU) && !defined(Q_CC_INTEL)
 #    pragma GCC diagnostic ignored "-Wstrict-overflow"
 #endif