$OpenBSD: patch-man_CMakeLists_txt,v 1.1 2021/02/05 14:30:39 sthen Exp $

just use the bundled manuals

Index: man/CMakeLists.txt
--- man/CMakeLists.txt.orig
+++ man/CMakeLists.txt
@@ -6,7 +6,7 @@
 
 if(NOT WIN32)
 	find_program(XSLTPROC xsltproc OPTIONAL)
-	if(XSLTPROC)
+	if(FALSE)
 		function(compile_manpage page)
 			add_custom_command(OUTPUT ${CMAKE_SOURCE_DIR}/man/${page}
 				COMMAND xsltproc ${CMAKE_SOURCE_DIR}/man/${page}.xml -o ${CMAKE_SOURCE_DIR}/man/
@@ -25,8 +25,6 @@ if(NOT WIN32)
 		compile_manpage("mosquitto-tls.7")
 		compile_manpage("mqtt.7")
 		compile_manpage("mosquitto.8")
-	else()
-		message(FATAL_ERROR "xsltproc not found: manpages cannot be built")
 	endif()
 
 endif()
