gcc: pass -Wno-complain-wrong-lang when using -fmacro-prefix-map

This will break GCC < 13 when compiled with LLVM, but those versions
are EOL and should be removed anyway, so I’m happy to do the nudge
rather than spend more effort on this hopefully‐temporary hack.

pkgs/development/compilers/gcc/common/builder.nix

@@ -126,6 +126,20 @@ originalAttrs:
               EXTRA_LDFLAGS_FOR_TARGET="$EXTRA_LDFLAGS"
           fi
 
+          # We include `-fmacro-prefix-map` in `cc-wrapper` for non‐GCC
+          # platforms only, but they get picked up and passed down to
+          # e.g. GFortran calls that complain about the option not
+          # applying to the language. Hack around it by asking GCC not
+          # to complain.
+          #
+          # TODO: Someone please fix this to do things that make sense.
+          if [[ $EXTRA_FLAGS_FOR_BUILD == *-fmacro-prefix-map* ]]; then
+              EXTRA_FLAGS_FOR_BUILD+=" -Wno-complain-wrong-lang"
+          fi
+          if [[ $EXTRA_FLAGS_FOR_TARGET == *-fmacro-prefix-map* ]]; then
+              EXTRA_FLAGS_FOR_TARGET+=" -Wno-complain-wrong-lang"
+          fi
+
           # CFLAGS_FOR_TARGET are needed for the libstdc++ configure script to find
           # the startfiles.
           # FLAGS_FOR_TARGET are needed for the target libraries to receive the -Bxxx