ci: add horrible hack to retry compilation on failure

it seems there's some race condition in the build system,
and the gen_init_cpio step fails on occasion.

because make is incremental, when the build is restarted it'll pick
straight back up at the failed step, and the problem will resolve.

a hacky fix sure, but good enough for now.

flake.nix

@@ -50,7 +50,14 @@
 
                 enableParallelBuilding = true;
                 configurePhase = "make HOSTCC=$HOSTCC -j$NIX_BUILD_CORES defconfig";
-                buildPhase = "make HOSTCC=$HOSTCC -j$NIX_BUILD_CORES -C tools/wasm";
+                buildPhase = "
+                  # this is a horrible dirty hack but there's some non-deterministic build failure
+                  for i in $(seq 1 3); do
+                    if make HOSTCC=$HOSTCC -j$NIX_BUILD_CORES -C tools/wasm; then
+                      break
+                    fi
+                  done
+                ";
                 installPhase = ''cp -r tools/wasm/dist $out'';
               };
             }