mediastreamer: fixup build with gcc 11

https://hydra.nixos.org/build/173781674

pkgs/development/libraries/mediastreamer/default.nix

@@ -92,12 +92,14 @@ stdenv.mkDerivation rec {
   # Do not build static libraries
   cmakeFlags = [ "-DENABLE_STATIC=NO" ];
 
-  NIX_CFLAGS_COMPILE = toString [
+  NIX_CFLAGS_COMPILE = [
     "-DGIT_VERSION=\"v${version}\""
     "-Wno-error=deprecated-declarations"
     "-Wno-error=cast-function-type"
     "-Wno-error=stringop-truncation"
     "-Wno-error=stringop-overflow"
+  ] ++ lib.optionals (stdenv.cc.isGNU && lib.versionAtLeast stdenv.cc.version "11") [
+    "-Wno-error=stringop-overread"
   ];
   NIX_LDFLAGS = "-lXext";