Fix the compilation under gcc 4.9.0.

gcc interpretes C99's compound literals more strictly by invalid the
compound literal on implicit to pointer cast (because of automatic
storage duration, 6.5.2.5.6 in C99 standard draft).

This fixes the issue by not using compound literals at all.

builtin.cpp

@@ -2636,7 +2636,13 @@ static int builtin_read(parser_t &parser, wchar_t **argv)
                 size_t j = 0;
                 for (; i+1 < argc; ++i)
                 {
-                    env_set(argv[i], j < bufflen ? (wchar_t[2]){buff[j], 0} : L"", place);
+                    if (j < bufflen) {
+                        wchar_t buffer[2] = {buff[j], 0};
+                        env_set(argv[i], buffer, place);
+                    }
+                    else {
+                        env_set(argv[i], L"", place);
+                    }
                     if (j < bufflen) ++j;
                 }
                 if (i < argc) env_set(argv[i], &buff[j], place);