Add build.zig to be able to use zig cc

We'll use this for cross compilation

.gitignore

@@ -2,3 +2,6 @@
 bin/
 build/
 .idea/
+zig-cache/
+zig-out/
+.DS_Store

build.zig

@@ -0,0 +1,19 @@
+const std = @import("std");
+
+pub fn build(b: *std.build.Builder) void {
+    // Standard release options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
+    const mode = b.standardReleaseOptions();
+
+    const lib = b.addStaticLibrary("MQTT-C", null);
+
+    lib.addIncludeDir("include");
+
+    lib.addCSourceFile("src/mqtt.c", &[_][]const u8 {});
+    lib.addCSourceFile("src/mqtt_pal.c", &[_][]const u8 {});
+
+    lib.linkLibC();
+
+    lib.setBuildMode(mode);
+    lib.install();
+}