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, 149 insertions, 0 deletions

diff --git a/tools/makehelp.sh b/tools/makehelp.sh
new file mode 100755
index 00000000..e6118de7
--- /dev/null
+++ b/tools/makehelp.sh
@@ -0,0 +1,149 @@
+#!/bin/sh
+set -eu
+
+. tools/lib.sh
+
+
+usage() {
+	cat <<-'EOF'
+		Usage:
+		  makehelp.sh < MAKEFILE
+		  makehelp.sh -h
+	EOF
+}
+
+help() {
+	cat <<-'EOF'
+
+
+		Options:
+		  -h, --help    show this message
+
+
+		Generate a help message from the given Makefile.
+
+		Any target or variable commented with two "#" characters gets
+		picked up.  Multi-line comments are supported:
+
+		  VAR1 = 1
+		  # a comment
+		  VAR2 = 2
+		  ## another comment -> this one is included in the docs
+		  VAR3 = 3
+
+		  ## with a big
+		  ## comment, which is also included
+		  a-target:
+
+
+		Examples:
+
+		  Generate help messages from "Makefile":
+
+		    $ aux/makehelp.sh < Makefile
+
+
+		  Generate help messages for all targets:
+
+		    $ cat Makefile dev.mk | aux/makehelp.sh
+	EOF
+}
+
+
+for flag in "$@"; do
+	case "$flag" in
+		(--)
+			break
+			;;
+		(--help)
+			usage
+			help
+			exit
+			;;
+		(*)
+			;;
+	esac
+done
+
+while getopts 'h' flag; do
+	case "$flag" in
+		(h)
+			usage
+			help
+			exit
+			;;
+		(*)
+			usage >&2
+			exit 2
+			;;
+	esac
+done
+shift $((OPTIND - 1))
+
+
+TARGETS="$(mkstemp)"
+VARIABLES="$(mkstemp)"
+trap 'rm -f "$TARGETS" "$VARIABLES"' EXIT
+
+awk -vCOLUMN=15 -vTARGETS="$TARGETS" -vVARIABLES="$VARIABLES" '
+function indent(n, where) {
+	for (INDENT = 0; INDENT < n; INDENT++) {
+		printf " " > where
+	}
+}
+
+/^## / { doc[len++] = substr($0, 4) }
+
+/^[-_a-zA-Z]+:/ && len {
+	printf "\033[36m%s\033[0m", substr($1, 1, length($1) - 1) > TARGETS
+	for (i = 0; i < len; i++) {
+		n = COLUMN - (i == 0 ? length($1) - 1 : 0)
+		indent(n, TARGETS)
+		printf "%s\n", doc[i] > TARGETS
+	}
+	len = 0
+}
+
+/^.++=/ && len {
+	printf "\033[36m%s\033[0m", $1 > VARIABLES
+	for (i = 0; i < len; i++) {
+		n = COLUMN - (i == 0 ? length($1) : 0)
+		indent(n, VARIABLES)
+		printf "%s\n", doc[i] > VARIABLES
+	}
+	len = 0
+}'
+
+
+
+indent() {
+	sed 's|^|  |'
+}
+
+cat <<-EOF
+	Usage:
+
+	  make [VARIABLE=value...] [target...]
+
+
+	Targets:
+
+	$(indent < "$TARGETS")
+
+
+	Variables:
+
+	$(indent < "$VARIABLES")
+
+
+	Examples:
+
+	  Build "all", the default target:
+
+	    $ make
+
+
+	  Test and install, with \$(DESTDIR) set to "tmp/":
+
+	    $ make DESTDIR=tmp check install
+EOF