Run missing documentation tools through "missing"

Instead of just erroring out when a tool is missing, wrap the call with
the "missing" script that we are already using for bison, flex, and
perl, so that the users get a useful error message.

configure

@@ -630,6 +630,7 @@ vpath_build
 PROVE
 OSX
 XSLTPROC
+DBTOEPUB
 COLLATEINDEX
 DOCBOOKSTYLE
 have_docbook
@@ -14406,6 +14407,48 @@ fi
 
 
 fi
+for ac_prog in dbtoepub
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_DBTOEPUB+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$DBTOEPUB"; then
+  ac_cv_prog_DBTOEPUB="$DBTOEPUB" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_DBTOEPUB="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+DBTOEPUB=$ac_cv_prog_DBTOEPUB
+if test -n "$DBTOEPUB"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $DBTOEPUB" >&5
+$as_echo "$DBTOEPUB" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$DBTOEPUB" && break
+done
+
 for ac_prog in xsltproc
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.

configure.in

@@ -1858,6 +1858,7 @@ PGAC_PROG_JADE
 PGAC_CHECK_DOCBOOK(4.2)
 PGAC_PATH_DOCBOOK_STYLESHEETS
 PGAC_PATH_COLLATEINDEX
+AC_CHECK_PROGS(DBTOEPUB, dbtoepub)
 AC_CHECK_PROGS(XSLTPROC, xsltproc)
 AC_CHECK_PROGS(OSX, [osx sgml2xml sx])
 

doc/src/sgml/Makefile

@@ -27,27 +27,29 @@ all: html man
 distprep: html distprep-man
 
 
+ifndef DBTOEPUB
+DBTOEPUB = $(missing) dbtoepub
+endif
+
 ifndef JADE
-JADE = jade
+JADE = $(missing) jade
 endif
 SGMLINCLUDE = -D . -D $(srcdir)
 
 ifndef NSGMLS
-NSGMLS = nsgmls
+NSGMLS = $(missing) nsgmls
 endif
 
 ifndef OSX
-OSX = osx
+OSX = $(missing) osx
 endif
 
 ifndef XSLTPROC
-XSLTPROC = xsltproc
+XSLTPROC = $(missing) xsltproc
 endif
 
 override XSLTPROCFLAGS += --stringparam pg.version '$(VERSION)'
 
-DBTOEPUB ?= dbtoepub
-
 
 GENERATED_SGML = bookindex.sgml version.sgml \
 	features-supported.sgml features-unsupported.sgml errcodes-table.sgml

src/Makefile.global.in

@@ -348,6 +348,7 @@ STRIP_SHARED_LIB = @STRIP_SHARED_LIB@
 
 have_docbook	= @have_docbook@
 COLLATEINDEX	= @COLLATEINDEX@
+DBTOEPUB	= @DBTOEPUB@
 DOCBOOKSTYLE	= @DOCBOOKSTYLE@
 JADE			= @JADE@
 NSGMLS			= @NSGMLS@