Remove fesrv

The build error of the application remained unattended for almost a
year.

Fixes #170

ports/fesrv.hash

@@ -1 +0,0 @@
-f3880fddb60b77e7af5bc03abfef751db0e1faf6

ports/fesrv.port

@@ -1,11 +0,0 @@
-LICENSE   := BSD
-VERSION   := ceb56f29aacf1ff8a9997e9a57b855936ba00fd6
-DOWNLOADS := riscv-fesrv.git
-
-URL(riscv-fesrv) := https://github.com/riscv/riscv-fesvr.git
-REV(riscv-fesrv) := ceb56f29aacf1ff8a9997e9a57b855936ba00fd6
-
-DIR(riscv-fesrv) := src/app/fesrv
-
-PATCHES := src/app/fesrv/patches/*.patch
-PATCH_OPT := -N -p1 -d ${DIR(riscv-fesrv)}