Remove unused gombile project

I went over our set of patch files and it seems we forgot to remove a bunch of them in the past:

find -type f -name build -exec grep "patch -" {} \; | wc -l
32

vs.

find -type f -name *.patch | wc -l
37

I took a quick look and at least

./kcp-go/remove-crypt-fec.patch
./gomobile/0001-If-the-GOMOBILE_TMPDIR-env-variable-is-defined-use-t.patch
./goutls/sessionid.patch

can go.