mysql55: fixup build with gcc7

+1
+1
pkgs/servers/sql/mysql/5.5.x.nix
··· 49 49 "-DINSTALL_SHAREDIR=share/mysql" 50 50 ]; 51 51 52 + NIX_CFLAGS_COMPILE = [ "-fpermissive" ]; # since gcc-7 52 53 NIX_LDFLAGS = stdenv.lib.optionalString stdenv.isLinux "-lgcc_s"; 53 54 54 55 prePatch = ''