option to not build man page

fixes #56

configure.ac

@@ -20,13 +20,28 @@ AC_CHECK_FILE(
   [src/pixz.1],
   [],
   [
-    AC_CHECK_PROG(A2X, a2x, a2x, [])
-    if test "x$A2X" = x ; then
-      AC_MSG_ERROR([AsciiDoc not found, not able to generate the man page.])
-    fi
+    AC_ARG_WITH(
+      [manpage],
+      [  --without-manpage       don't build man page],
+      [case ${withval} in
+        yes) manpage=true ;;
+        no)  manpage=false ;;
+        *)   AC_MSG_ERROR([bad value ${withval} for --with-manpage]) ;;
+      esac],
+      [manpage=true]
+    )
   ]
 )
 
+AM_CONDITIONAL([MANPAGE], [test x$manpage = xtrue])
+
+if test x$manpage = xtrue ; then
+  AC_CHECK_PROG(A2X, a2x, a2x, [])
+  if test "x$A2X" = x ; then
+    AC_MSG_ERROR([AsciiDoc not found, not able to generate the man page.])
+  fi
+fi
+
 # Checks for libraries.
 AC_CHECK_LIB([m], [ceil])
 AX_PTHREAD

src/Makefile.am

@@ -15,6 +15,7 @@ pixz_SOURCES = \
 	read.c \
 	write.c
 
+if MANPAGE
 # TODO remove when possible: This is a hack because a2x is not able to output the man pages to a
 # specific directory, only to where the source is.
 pixz.1: pixz.1.asciidoc
@@ -26,3 +27,4 @@ man_MANS = pixz.1
 CLEANFILES = pixz.1
 
 EXTRA_DIST = $(man_MANS) pixz.1.asciidoc
+endif