fix disableFpe() for clang

fwk/src/fwk.cpp

@@ -48,8 +48,10 @@ FWK_API void enableFpe()
  */
 FWK_API void disableFpe()
 {
-#if defined(__GNUC__)
+#if defined(__GNUC__) && !defined(__clang__)
     std::cout << ANSI_COLOR_BLUE << "Disabling Floating-Point Exceptions..." << ANSI_COLOR_RESET << std::endl;
     fedisableexcept(FE_ALL_EXCEPT);
+#else
+    std::cout << "disableFpe() is not implemented" << std::endl;
 #endif
 }
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