added cmake as an optional build tool

c/CMakeLists.txt

@@ -0,0 +1,37 @@
+cmake_minimum_required(VERSION 4.0)
+project(ttk91_compiler C CXX)
+
+# https://cmake.org/cmake/help/latest/module/FindBISON.html
+find_package(BISON)
+bison_target(
+    ttk91_parser                        # name
+    src/parser.bison                    # input .bison file
+    src/parser.c                        # output .c
+    DEFINES_FILE include/token.h        # output .h
+    OPTIONS -Wall -t                    # options
+)
+
+find_package(FLEX)
+flex_target(
+    ttk91_scanner # name
+    scanner.flex # input
+    scanner.c # output
+    OPTIONS --warn
+)
+
+set(SOURCES
+    src/main.c
+    src/parser.c
+    src/scanner.c
+    src/program.c
+    src/expr.c
+    src/oper.c
+    src/ttk_register.c
+    src/label.c
+    src/value.c
+    src/comment.c
+)
+
+add_executable(ttk91_compiler ${SOURCES})
+
+target_include_directories(ttk91_compiler PRIVATE include)