monotone: fix build for upcoming gcc-14

Without the change build fails as:

    In file included from /<<NIX>>/gcc-14.0.0/include/c++/14.0.0/limits:42,
                     from <stdin>:1:
    /<<NIX>>/gcc-14.0.0/include/c++/14.0.0/x86_64-unknown-linux-gnu/bits/c++config.h:668:2: warning: #warning "__STRICT_ANSI__ seems to have been undefined; this is not supported" [-Wcpp]
      668 | #warning "__STRICT_ANSI__ seems to have been undefined; this is not supported"
          |  ^~~~~~~
    /<<NIX>>/gcc-14.0.0/include/c++/14.0.0/limits:2100:30: error: exponent has no digits
     2100 |         return __extension__ 0x1.0p-16382Q;
          |                              ^~~~~~
    /<<NIX>>/gcc-14.0.0/include/c++/14.0.0/limits:2114:30: error: exponent has no digits
     2114 |         return __extension__ 0x1.ffffffffffffffffffffffffffffp+16383Q;

gcc upstream confirms unsetting __STRICT_ANSI__ is an unsupported
configuration: https://gcc.gnu.org/PR111824

pkgs/applications/version-management/monotone/default.nix

@@ -40,6 +40,7 @@ stdenv.mkDerivation rec {
       revert = true;
       sha256 = "0fzjdv49dx5lzvqhkvk50lkccagwx8h0bfha4a0k6l4qh36f9j7c";
     })
+    ./monotone-1.1-gcc-14.patch
   ];
 
   postPatch = ''

pkgs/applications/version-management/monotone/monotone-1.1-gcc-14.patch

@@ -0,0 +1,17 @@
+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>
+