build: add hand-rolled make scaffold (gmake/bmake/build.sh/build.bat)

Static-lib-only build (libfpk.a, no shared/dynamic target), plus a
tools/ build path for fpack/funpack linked against the just-built
static lib. Matches stk's C89 build style; no library source yet.

build.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+
+OS=$(uname -s | tr '[:upper:]' '[:lower:]')
+
+if [ "$OS" = "linux" ]; then
+	MK_FILE="gmake.mk"
+else
+	MK_FILE="bmake.mk"
+fi
+
+HAS_INSTALL=0
+HAS_UNINSTALL=0
+for arg in "$@"; do
+	case "$arg" in
+		install)   HAS_INSTALL=1 ;;
+		uninstall) HAS_UNINSTALL=1 ;;
+	esac
+done
+
+if [ "$HAS_INSTALL" = "1" ] || [ "$HAS_UNINSTALL" = "1" ]; then
+	if [ "$HAS_INSTALL" = "1" ]; then
+		make -f "$MK_FILE" release
+	fi
+
+	if [ "$(id -u)" = "0" ]; then
+		PRIV=""
+	elif command -v doas > /dev/null 2>&1; then
+		PRIV="doas"
+	elif command -v sudo > /dev/null 2>&1; then
+		PRIV="sudo"
+	else
+		echo "error: install requires root. neither doas nor sudo found." >&2
+		exit 1
+	fi
+
+	$PRIV make -f "$MK_FILE" "$@"
+else
+	make -f "$MK_FILE" "$@"
+fi