hidden "missing override" warning in GenericXD histogram headers for GCC

in those classes the override is needed or not depending on the teplpate
parameter, so the only solution is to hide the warning.

GaudiCommonSvc/src/HistogramSvc/Generic1D.h

@@ -11,11 +11,14 @@
 #include "AIDA/IProfile1D.h"
 #include "TFile.h"
 
-#ifdef __clang__
-#pragma clang diagnostic push
 // Hide warning message:
 // warning: 'XYZ' overrides a member function but is not marked 'override'
+#ifdef __clang__
+#pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Winconsistent-missing-override"
+#elif defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsuggest-override"
 #endif
 
 namespace Gaudi {
@@ -239,6 +242,8 @@ namespace Gaudi {
 
 #ifdef __clang__
 #pragma clang diagnostic pop
+#elif defined(__GNUC__)
+#pragma GCC diagnostic pop
 #endif
 
 #endif // AIDAROOT_GENERIC1D_H

GaudiCommonSvc/src/HistogramSvc/Generic2D.h

@@ -11,12 +11,14 @@
 #include "Axis.h"
 #include "TFile.h"
 
-
-#ifdef __clang__
-#pragma clang diagnostic push
 // Hide warning message:
 // warning: 'XYZ' overrides a member function but is not marked 'override'
+#ifdef __clang__
+#pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Winconsistent-missing-override"
+#elif defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsuggest-override"
 #endif
 
 namespace Gaudi {
@@ -366,6 +368,8 @@ namespace Gaudi {
 
 #ifdef __clang__
 #pragma clang diagnostic pop
+#elif defined(__GNUC__)
+#pragma GCC diagnostic pop
 #endif
 
 #endif // GAUDIPI_GENERIC2D_H

GaudiCommonSvc/src/HistogramSvc/Generic3D.h

@@ -11,11 +11,14 @@
 #include <stdexcept>
 #include <memory>
 
-#ifdef __clang__
-#pragma clang diagnostic push
 // Hide warning message:
 // warning: 'XYZ' overrides a member function but is not marked 'override'
+#ifdef __clang__
+#pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Winconsistent-missing-override"
+#elif defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsuggest-override"
 #endif
 
 namespace Gaudi {
@@ -324,6 +327,8 @@ namespace Gaudi {
 
 #ifdef __clang__
 #pragma clang diagnostic pop
+#elif defined(__GNUC__)
+#pragma GCC diagnostic pop
 #endif
 
 #endif // GAUDIPI_GENERIC3D_H