* make/check.make: Skip if CC is not set.
* make/check-mlibc.make: New file.
* scaffold/scaffold.make: Use it for mlibc targets.
* tinycc/tinycc.make: Skip mlibc targets if CC32 not set.
* GNUmakefile (OUT,QUIET,SUBDIRS): New variables.
include make/common.make
* .gitignore: Remove toplevel targets.
* build-aux/compile-all.scm: Import from GNU Guix.
* configure (gulp-pipe): Check exit status. Actually test for CC,
CC32.
* make/bin.make: New file.
* make/check.make: New file.
* make/clean.make: New file.
* make/common.make: New file.
* make/compile.make: New file.
* make/guile.make: New file.
* make/mescc-guile.make: New file.
* make/mescc-mes.make: New file.
* make/reset.make: New file.
* lib/mlibc.c: Rename from top.
* lib/start.c: Rename from top.
* module/module.make: New file.
* scaffold/scaffold.make: New file.
* scripts/scripts.make: New file.
* src/mes.c: Rename from top.
* src/src.make: New file.
* src/mes.c: Rename from top.
* src/gc..c: Rename from top.
* src/lib.c: Rename from top.
* src/posix.c: Rename from top.
* src/reader.c: Rename from top.
* src/vector.c: Rename from top.
* tests/tests.make: New file.