use lv2.h provided at root of /usr/include

fixes ubuntu issues

.gitignore

@@ -1,3 +1,4 @@
 zig-cache/
 *.mp3
 *.wav
+build_runner.zig

build.zig

@@ -13,23 +13,30 @@ fn setupLinks(step: *builds.LibExeObjStep) void {
     step.linkSystemLibrary("GraphicsMagick");
 
     step.addIncludeDir("/usr/include/GraphicsMagick");
+    step.addIncludeDir("/usr/include");
 
     const possible_lilv_include_dirs = [_][]const u8{
-        "/usr/include/lilv-0",
         "/usr/include/lilv-0/lilv",
+        "/usr/include/lilv-0",
     };
+
     var found_any_lilv = false;
 
     for (possible_lilv_include_dirs) |possible_lilv_dir| {
-        var possible_dir = std.fs.cwd().openDir(possible_lilv_dir) catch |err| {
+        var possible_dir = std.fs.cwd().openDir(possible_lilv_dir, .{}) catch |err| {
+            std.debug.warn("possible lilv {} fail: {}\n", .{ possible_lilv_dir, err });
             continue;
         };
+
         possible_dir.close();
         found_any_lilv = true;
+
+        std.debug.warn("found lilv at '{}'\n", .{possible_lilv_dir});
+        step.addIncludeDir(possible_lilv_dir);
     }
 
     if (!found_any_lilv) {
-        std.debug.warn("No LILV library was found :(\n");
+        std.debug.warn("No LILV library was found :(\n", .{});
         @panic("no lilv found");
     }
 }

src/lv2_helpers.zig

@@ -4,7 +4,7 @@ const plugin = @import("plugin.zig");
 pub const c = @cImport({
     @cInclude("sndfile.h");
     @cInclude("lilv/lilv.h");
-    @cInclude("lv2/core/lv2.h");
+    @cInclude("lv2.h");
 });
 
 pub fn Lv2Core(comptime ns: []const u8) []const u8 {