generate manpages with pod2man instead of a2x/asciidoc(tor)

it turned out that the upstream section in tinyproxy.conf.5 wasn't rendered
properly, because in asciidoc items following a list item are always explicitly
appended to the last list item.
after several hours of finding a workaround, it was decided to change the
manpage generator to pod2man instead.

as pod2man ships together with any perl base install, it should be available
on almost every UNIX system, unlike asciidoc which requires installation
of a huge set of dependencies (more than 1.3 GB on Ubuntu 16.04), and the
replacement asciidoctor requires a ruby installation plus a "gem" (which is
by far better than asciidoc, but still more effort than using the already
available pod2man).

tinyproxy's hard requirement of a2x (asciidoctor) for building  from source
caused rivers of tears (and dozens of support emails/issues) in the past, but
finally we get rid of it. a tool such as a2x with its XML based bloat-
technology isn't really suited to go along with a supposedly lightweight
C program.

if it ever turns out that even pod2man is too heavy a dependency, we could
still write our own replacement in less than 50 lines of awk, as the pod
syntax is very low level and easy to parse.

1 files changed, 8 insertions, 29 deletions

diff --git a/configure.ac b/configure.ac
index e645dc1..900af95 100644
--- a/configure.ac
+++ b/configure.ac
@@ -97,9 +97,9 @@ if test x"$transparent_enabled" = x"yes"; then
 fi
 
 dnl Let user decide whether he wants support for manpages
-dnl Which require either a2x/asciidoctor or a tarball release
+dnl Which require either pod2man or a tarball release
 AH_TEMPLATE([MANPAGE_SUPPORT],
-	    [Build manpages with a2x/asciidoctor if they are missing from the distribution.])
+	    [Build manpages with pod2man if they are missing from the distribution.])
 TP_ARG_ENABLE(manpage_support,
               [Enable support for building manpages (default is YES)],
               yes)
@@ -183,39 +183,18 @@ AC_SUBST(LIBS)
 AC_SUBST(ADDITIONAL_OBJECTS)
 
 if test x"$manpage_support_enabled" = x"yes"; then
-# Check for asciidoc
-AC_PATH_PROG(A2X, a2x, no)
-if test "x$A2X" = "xno" ; then
-# Check for asciidoctor
-AC_PATH_PROG(ASCIIDOCTOR, asciidoctor, no)
-else
-# checking xmllint, which is only used together with a2x
-AC_PATH_PROG(XMLLINT, xmllint, no)
-if test "x$XMLLINT" != "xno"; then
-  AS_ECHO_N("testing xmllint... ")
-  echo "TEST" > conftest.txt
-  if $A2X -f docbook conftest.txt 2>/dev/null; then
-    AS_ECHO("ok")
-  else
-    AS_ECHO("failed")
-    XMLLINT="no"
-  fi
-  rm -f conftest.txt conftest.xml
-fi
-fi #a2x installed
+AC_PATH_PROG(POD2MAN, pod2man, no)
 
-if test "x$A2X" = "xno" -a "x$ASCIIDOCTOR" = "xno" && \
+if test "x$POD2MAN" = "xno" && \
  ! test -e docs/man5/tinyproxy.conf.5 -a -e docs/man8/tinyproxy.8 ; then
 AC_MSG_ERROR([
-  manpage generation requested, but neither a2x, asciidoctor
+  manpage generation requested, but neither pod2man
   nor pre-generated manpages found.
   Use --disable-manpage-support if you want to compile anyway.])
 fi
 fi #manpage_support_enabled
 
-AM_CONDITIONAL(HAVE_A2X, test "x$A2X" != "x" -a "x$A2X" != "xno")
-AM_CONDITIONAL(HAVE_XMLLINT, test "x$XMLLINT" != "x" -a "x$XMLLINT" != "xno")
-AM_CONDITIONAL(HAVE_ASCIIDOCTOR, test "x$ASCIIDOCTOR" != "x" -a "x$ASCIIDOCTOR" != "xno")
+AM_CONDITIONAL(HAVE_POD2MAN, test "x$POD2MAN" != "x" -a "x$POD2MAN" != "xno")
 
 AC_CONFIG_FILES([
 Makefile
@@ -237,12 +216,12 @@ scripts/Makefile
 AC_OUTPUT
 
 # the manpages are shipped in the release tarball and we don't want them to
-# get regenerated if a2x is not available. the intermediate files from
+# get regenerated if pod2man is not available. the intermediate files from
 # AC_CONFIG_FILES are created with config.status, which is created at configure
 # runtime, so we need to touch them after config.status terminated to prevent
 # make from rebuild them.
 
-if test "x$A2X" = "xno" -a "x$ASCIIDOCTOR" = "xno" ; then
+if test "x$POD2MAN" = "xno" ; then
   touch docs/man5/tinyproxy.conf.txt
   touch docs/man8/tinyproxy.txt
   if test -e docs/man5/tinyproxy.conf.5 ; then