Rodrigo Mesquita authored May 28, 2024 and Marge Bot committed Jun 24, 2024

It is non-obvious whether the toolchain configuration should use
full-paths to tools or simply their names. In addressing #24574, we've
decided to prefer executable names over paths, ultimately, because the
bindist configure script already does this, thus is the default in ghcs
out there.

Updates the in-tree configure script to prefer tool names
(`AC_CHECK_TOOL` rather than `AC_PATH_TOOL`) and `ghc-toolchain` to
ignore the full-path-result of `findExecutable`, which it previously
used over the program name.

This change doesn't undo the fix in bd92182c
because `AC_CHECK_TOOL` still takes into account the target triples,
unlike `AC_CHECK_PROG/AC_PATH_PROG`.