[xml] [patch] add a --disable-rebuild-docs configure option

[Adrian Bunk <adrian bunk movial fi>]

The Matrix tool [1] used in the ARM Linux Internet Platform [2] checks 
during builds whether shipped files have changed since the last build. 
This catches situations where people forgot to push local changes to the 
repository. It is very uncommon that software modifies shipped files 
during the build. Unfortunately, documentation files shipped in the 
libxml2 SVN get rebuild during a normal build.

[1] http://sandbox.movial.com/wiki/index.php/Matrix
[2] http://linux.onarm.com


With --disable-rebuild-docs shipped files will no longer change during 
the build.

By default, the files will still get rebuilt.

--- a/configure.in
+++ b/configure.in
@@ -166,6 +166,10 @@ AC_ARG_WITH(zlib,
 AC_ARG_WITH(coverage,
 [  --with-coverage         build for code coverage with GCC (off)])
 
+AC_ARG_ENABLE(rebuild-docs,
+[  --enable-rebuild-docs[[=yes/no]]  rebuild some generated docs [[default=yes]]])
+AM_CONDITIONAL([REBUILD_DOCS], [test "$enable_rebuild_docs" = "no"])
+
 dnl
 dnl hard dependancies on options
 dnl
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -26,7 +26,11 @@ EXTRA_DIST=xmlcatalog_man.xml tutorial/*.html tutorial/*.c tutorial/*.pdf \
 
 man_MANS = xmllint.1 xmlcatalog.1
 
+if REBUILD_DOCS
 all: web $(top_builddir)/NEWS libxml2.xsa $(man_MANS)
+else
+all:
+endif
 
 api: libxml2-api.xml libxml2-refs.xml $(APIPAGES) $(srcdir)/html/index.html $(WIN32_DIR)/libxml2.def.src 
../elfgcchack.h