build: convert build system to CMake

tools/CMakeLists.txt

@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.13)
+project(magenta-tools C)
+
+set(tool_dirs e64patch)
+
+foreach (dir ${tool_dirs})
+	add_subdirectory(${dir})
+endforeach (dir)

tools/e64patch/CMakeLists.txt

@@ -0,0 +1,3 @@
+file(GLOB sources *.c *.h)
+
+add_executable(e64patch ${sources})