cleanup: Remove old donut/xl code and erasure implementation.

This is a change to bring in 'klauspost/reedsolomon' library
in #1270 patch.

buildscripts/checkdeps.sh

@@ -21,7 +21,6 @@ _init() {
 
     ## Minimum required versions for build dependencies
     GIT_VERSION="1.0"
-    YASM_VERSION="1.2.0"
     GO_VERSION="1.6"
     OSX_VERSION="10.8"
     UNAME=$(uname -sm)
@@ -184,11 +183,6 @@ check_deps() {
     if [ $? -ge 2 ]; then
         MISSING="${MISSING} git"
     fi
-
-    check_version "$(env yasm --version 2>/dev/null | sed 's/^.* \([0-9.]*\).*$/\1/' | head -1)" "${YASM_VERSION}"
-    if [ $? -ge 2 ]; then
-        MISSING="${MISSING} yasm(${YASM_VERSION})"
-    fi
 }
 
 main() {