[libxslt] Add --enable-rebuild-docs configure option

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 161b521c5b2a1e34d42ae372e9521208b7d4edde
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sun Feb 13 00:46:50 2022 +0100

    Add --enable-rebuild-docs configure option
    
    Don't rebuild documentation by default. This should only be done by
    maintainers.

 configure.ac    | 7 +++++++
 doc/Makefile.am | 4 ++++
 2 files changed, 11 insertions(+)
---
diff --git a/configure.ac b/configure.ac
index 9a514c6a..24861345 100644
--- a/configure.ac
+++ b/configure.ac
@@ -109,6 +109,13 @@ AC_ARG_WITH(html-subdir, AS_HELP_STRING([--with-html-subdir=path],
 
 AC_SUBST(HTML_DIR)
 
+AC_ARG_ENABLE(rebuild-docs,
+[  --enable-rebuild-docs[[=yes/no]]  rebuild some generated docs [[default=no]]])
+if test "$enable_rebuild_docs" = "yes" -a "$srcdir" != "."; then
+  AC_MSG_ERROR([cannot rebuild docs when builddir != srcdir])
+fi
+AM_CONDITIONAL([REBUILD_DOCS], [test "$enable_rebuild_docs" = "yes"])
+
 dnl
 dnl Check the environment
 dnl
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 3d5364ca..13d8c3c7 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -136,6 +136,8 @@ EXTRA_DIST =                                \
 
 man_MANS = xsltproc.1
 
+if REBUILD_DOCS
+
 all-local:     web ../NEWS libxslt.xsa $(man_MANS)
 
 api:   libxslt-api.xml libxslt-refs.xml $(APIPAGES) search.php \
@@ -306,6 +308,8 @@ check-extra-dist:
                test -n "$$present" || echo "not in EXTRA_DIST: $$a" ; \
        done
 
+endif
+
 install-data-local:
        $(MKDIR_P) $(DESTDIR)$(HTML_DIR)
        -$(INSTALL) -m 0644 $(srcdir)/*.html $(DESTDIR)$(HTML_DIR)