meson: add switch to disable docs

the make build system can do this too.

Change-Id: I8c07d159cab54a8749c50dc33615f60bd251a86d

meson.build

@@ -71,6 +71,7 @@ foreach optname : path_opts
   endif
 endforeach
 
+enable_docs = get_option('enable-docs')
 
 enable_tests = get_option('enable-tests')
 
@@ -357,7 +358,10 @@ endif
 subdir('src')
 subdir('scripts')
 subdir('misc')
+
+if enable_docs
   subdir('doc/manual')
+endif
 
 if enable_tests
   subdir('tests/unit')

meson.options

@@ -46,3 +46,7 @@ option('state-dir', type : 'string', value : '/nix/var',
 option('log-dir', type : 'string', value : '/nix/var/log',
   description : 'path to store logs in for Nix',
 )
+
+option('enable-docs', type : 'boolean', value : true,
+  description : 'whether to build documentation',
+)