Revert "Revert "Utils: Remove old compiler support code""

Thomas provided a smaller fix.
This reverts commit 78fb7f44bf.

Change-Id: I1edff6477526fe4ce29df38852f47fe49117561e
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/libs/utils/smallstringview.h

@@ -31,16 +31,6 @@
 
 #include <cstring>
 
-#pragma push_macro("constexpr")
-#ifndef __cpp_constexpr
-#define constexpr
-#endif
-
-#pragma push_macro("noexcept")
-#ifndef __cpp_noexcept
-#define noexcept
-#endif
-
 namespace Utils {
 
 class SmallStringView
@@ -135,6 +125,3 @@ bool operator!=(const SmallStringView& first, const SmallStringView& second) noe
 }
 
 } // namespace Utils
-
-#pragma pop_macro("noexcept")
-#pragma pop_macro("constexpr")