Unsetting __STRICT_ANSI__ is not a supported configuration for gcc
nowadays. gcc-14 started failing libstdc++ build as it uses gcc
extensions without __STRICT_ANSI__: https://gcc.gnu.org/PR111824
--- a/src/base.hh
+++ b/src/base.hh
@@ -34,11 +34,6 @@
 #define WIN32_LEAN_AND_MEAN
 #endif
 
-// Cygwin somehow enables strict ansi, which we don't want.
-#ifdef __STRICT_ANSI__
-#undef __STRICT_ANSI__
-#endif
-
 #include <iosfwd>
 #include <string>  // it would be nice if there were a <stringfwd>