Ports: Remove the obsolete howto guide from cmake

We have long been able to build CMake fully on the host.

Ports/cmake/howto.md

@@ -1,40 +0,0 @@
-## Build Guide
-
-- Run `./package.sh` here, which should install the dependencies and copy the patched source code to `~anon/Source/cmake`
-- Give the vm at least 2G of RAM, and at least 1.5G of free disk space (actual values used may be different, but ~1.3GiB of RAM and 1.2GiB of disk space has been observed)
-- Build the bootstrap cmake binary:
-```sh
-$ cd Source/cmake
-$ ./bootstrap
-```
-- Go entertain yourself for a few minutes (build takes about 10m)
-- The bootstrap binary should be built, but may fail for any of the reasons detailed in [Troubleshooting](#troubleshooting).
-- Build and install cmake (this takes a long time, about 80 minutes on my machine)
-```sh
-$ make
-# mount -o bind /usr /usr
-# make install
-```
-- Optionally, add `/usr/local/bin` to PATH:
-```sh
-$ export PATH="$PATH:/usr/local/bin"
-```
-- Hopefully look back at the experience and laugh at its ease
-
-## Current Status
-
-Fully working :P
-
-## Troubleshooting
-
-### "Failed to open check cache file for write..." while bootstrap cmake is configuring cmake
-
-The cause for this is unknown, but it seems to be a transitive state; simply restarting the bootstrap process fixes it:
-```sh
-$ Bootstrap.cmk/cmake . -C Bootstrap.cmk/InitialCacheFlags.cmake -G 'Unix Makefiles' -DCMAKE_BOOTSTRAP=1 -DBUILD_TESTING=0
-```
-You might have to repeat this many times.
-
-### "unable to rename '...', reason: File already exists" while making cmake
-
-Cause unknown. re-running make made it go away.