meson: make asciidoc optional

it should be under an option like autoconf, but cba to do that now, and
this is an improvement over the status quo.

diff --git a/meson.build b/meson.build
index c1fdce8136cd693013941d3e87b13ebba79dba77..cac9da5ab89a6fc2d1dc672bbe1e143be5de1bf0 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -3051,7 +3051,7 @@ if build_libuuid
     'libuuid/man/uuid_generate_time_safe.3']
 endif
 
-asciidoctor = find_program('asciidoctor')
+asciidoctor = find_program('asciidoctor', required : false)
 if asciidoctor.found()
   foreach adoc : manadocs
     name = adoc.split('/')[-1]