Fix the build system.

The improvements are:

- use most of the default "Makefile" for standard packaging;
- also use the default ".gitignore" with for the derived assets;
- don't impose so many $CFLAGS on the user.  GCC still needs to be given
  the `-ffreestanding` flag explicitly for us to get a good binary;
- stop using ad-hoc tools/* scripts, and avoid the code-generation
  anti-pattern overall on the build.  Some of the generated files were
  checked-in, and some were removed;
- remove empty files;
- use POSIX make(1) over gmake;
- add fuzz targets;
- partial "install" and "uninstall" targets;
- complete "clean" target.

The shortcomings are:
- only working on x86_64.  More platforms coming soon;
- code is still messy: way too many warnings, GNU/BSD specific
  extensions, inline assembly, and all kinds of unportable code;
- still only works with GCC and GCC-like compilers, and completly fails
  with tcc(1) and cproc(1);
- the `deps.mk` file is being maintained manually.  As I work on the
  source files I'll finish automating its generation with `mkdeps.sh`;
- still seems to be coupled with Linux;
- still is missing tests setup;
- still uses `#include <$NAME.h>` instead of the correct
  `#include "$NAME.h"` form.

The generated libgrovel.a did match the previous lib/libc.a 100%.

1 files changed, 12 insertions, 6 deletions

diff --git a/.gitignore b/.gitignore
index e9e283b0..2466ce8d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,13 @@
+/*.a
+/src/config.h
 *.o
-*.lo
-*.a
-*.so
-*.so.1
-lib/musl-gcc.specs
-/obj/
+*.to
+*.xa
+*.bin
+/src/*.c.txt
+/src/*.cat
+/doc/*.[0-9]
+/tests/fuzz/*.o
+/tests/fuzz/*.xa
+/tests/fuzz/*.bin
+/tests/fuzz/corpus/