Update cosmocc to use superconfigure z0.0.23

tool/cosmocc/fetch.sh

@@ -0,0 +1,64 @@
+#!/bin/sh
+# tool/cosmocc/fetch.sh
+# sets up mono repo to use latest cosmocc toolchain
+
+URL=https://cosmo.zip/pub/cosmocc/cosmocc.zip
+
+echo creating o/third_party/gcc... >&2
+rm -rf o/third_party/gcc || exit
+mkdir -p o/third_party/gcc || exit
+cd o/third_party/gcc
+
+echo downloading $URL... >&2
+if command -v wget >/dev/null; then
+  wget $URL || exit
+else
+  curl -Lo cosmocc.zip $URL || exit
+fi
+
+echo extracting cosmocc.zip... >&2
+unzip cosmocc.zip || exit
+rm -f cosmocc.zip
+
+# report success and give tips
+cat <<'EOF' >&2
+
+SUCCESS
+
+  the cosmo mono repo will now build using cosmocc
+
+WARNING
+
+  if you run `make clean` then you'll have to download it again
+
+CONSIDER
+
+  you can install the cosmocc toolchain you just downloaded as follows
+
+    sudo chmod 01777 /opt
+    rm -rf /opt/cosmocc
+    mv o/third_party/gcc /opt/cosmocc
+    ln -sf /opt/cosmocc o/third_party/gcc
+    echo 'export PATH="/opt/cosmocc/bin:$PATH"' >>~/.profile
+
+  then just recreate the symlink after cleaning. please note that you
+  should NEVER need to use make clean with the cosmo mono repo, since
+  our Makefile is flawless. if make clean actually helps, file a bug.
+
+EOF
+
+# give tip to linux users
+if [ x"$(uname -s)" = x"Linux" ]; then
+  cat <<'EOF' >&2
+PROTIP
+
+  running these commands
+
+    rm -rf o
+    sudo mount -t tmpfs -o size=10G,noatime,nodiratime /dev/shm o
+    ln -sf /opt/cosmocc o/third_party/gcc
+
+  makes the mono repo build faster
+
+EOF
+fi