Also test make clean in library

Don't test `make clean` at the toplevel, that would be too much work (we'd
need to support `$(RM)` in all makefiles, and arrange for `find` as well for
`clean_more_on_top`).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/scripts/components-build-system.sh

@@ -50,6 +50,8 @@ component_build_make_no_gen_files () {
     # GCC needs "as" in $PATH by default. To use GCC, we need to tell it where
     # to find the assembler. Or we can use clang which just works.
     CC="$(command -v clang)"
+    # For cleaning.
+    RM="$(command -v rm)"
 
     # Test the build with make.
     # Preferably we should also test with CMake. Note that a CMake test