Revert "meson: use absolute cross-compiler paths"

Revert "meson: use absolute cross-compiler paths"

This reverts commit fc8e5d7c13f62e987b76971116cf290fd01a0c8f.

We need to use the absolute path to the compiler so that the VSCode
configuration generated by devtool ide-sdk could lint meson projects.

A feature was just added to vscode-cpptools to support conveying the
compilerPath in addition to the compile_commands.json. The next
commits adds the necessary configuration. We can revert this one and
keep the meson paths as they were.

Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>