Enable unity builds by default

CHANGELOG.md

@@ -53,6 +53,11 @@ TODO: Add an updated screenshot with some fancy VST3-only plugins to the readme
   and up. The build process now detect which version of Wine is used to build
   with, and it then applies the change conditionally to be able to support
   building with both older and newer versions of Wine.
+- [Unity builds](https://mesonbuild.com/Unity-builds.html) with 4-file units are
+  now enabled by default since all the source code additions for VST3 support
+  increased build times significantly. The unit size can be changed at build
+  time using the `unity_size` option, and this behaviour can be disabled
+  completely by passing `unity=off`.
 
 ### Fixed
 

meson.build

@@ -2,7 +2,16 @@ project(
   'yabridge',
   'cpp',
   version : '2.2.1',
-  default_options : ['warning_level=3', 'cpp_std=c++2a', 'build.cpp_std=c++2a'],
+  default_options : [
+    'warning_level=3',
+    'cpp_std=c++2a',
+    # Even though Meson will complain that this option does not exist, without
+    # this Meson will not apply the above option to native targets
+    'build.cpp_std=c++2a',
+    # Enable Unity builds with the default 4-file units to somewhat speed up the
+    # compilation process
+    'unity=on',
+  ],
 )
 
 # Meson does not let us set a default cross compiler, which makes sense, but it