Revert "Disable coreutils on M1 Apple Silicon with arm64 (#2020)" (#2212)

This reverts commit 90d0d20508.

After further consideration, we've decided to remove this workaround:
* It only has an effect if the user has added `gnubin` from Homebrew Coreutils to PATH which is an unsupported setup
* It was intended to be applied only to a few select 3.8 and 3.9 versions that officially support Apple Silicon and only fail with Homebrew Coreutils in PATH because they have `config.*` from a too old version of Autoconf that doesn't support the Arm64 arch -- but
  * CPython devs [didn't actually fix the problem in 3.10, either, only in 3.11](https://github.com/pyenv/pyenv/pull/2157#issuecomment-968055387), so we'd need to apply it to all 3.10 releases, too
  * users started pushing this workaround into other unrelated branches because they were using the above unsupported setup. See https://github.com/pyenv/pyenv/pull/2190#pullrequestreview-835221952 for discussion.

plugins/python-build/bin/python-build

@@ -112,13 +112,6 @@ is_mac() {
   [ $# -eq 0 ] || [ "$(osx_version)" "$@" ]
 }
 
-is_arm64_apple() {
-  if [ "$(uname -s)" = "Darwin" ] && [ "$(uname -m)" = "arm64" ]; then
-    return 0
-  fi
-  return 1
-}
-
 #  9.1  -> 901
 # 10.9  -> 1009
 # 10.10 -> 1010
@@ -1617,29 +1610,6 @@ use_tcltk() {
   fi
 }
 
-# CPython 3.9.1+ and 3.8.10+ have old config.sub that doesn't support "arm64" arch
-# which is what Gnu uname (but not Apple uname) produces on Apple M1
-# (https://github.com/pyenv/pyenv/pull/2020#issuecomment-891911842)
-build_package_arm64_apple_disable_homebrew_coreutils() {
-  if is_arm64_apple; then
-    local brew_coreutils="$(brew --prefix coreutils 2>/dev/null || true)"
-    if [ -d "$brew_coreutils" ]; then
-      local after_list=()
-      # Bash 3 ignores IFS set for command when doing expansions so have to set it separately
-      IFS=':'; local -a list=(${PATH}); IFS="$OLDIFS"
-      for str in "${list[@]}"; do
-        if [[ "$str" != "$brew_coreutils"/* ]]; then
-          after_list+=("$str")
-        else
-          echo "python-build: excluding \`$str' from PATH"
-        fi
-      done
-      # Bash 3 ignores IFS set for command when doing expansions so have to set it separately
-      IFS=':'; export PATH="${after_list[*]}"; IFS="$OLDIFS"
-    fi
-  fi
-}
-
 build_package_enable_shared() {
     package_option python configure --enable-shared
 }