Fix some trivial typos.
build: Reorder tools dependencies for correct build ordering.

The tools-configure target requires a completed llvm build.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build: Remove some duplicate order-only prerequisites on the stamps dir

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build: Refactor duplicated stp dependency declaration on CLANG_CXX

Signed-off-by: Diego Biurrun <diego@biurrun.de>