disallow includedir /usr/include

Hi again!

Current SVN head fails to do "make install" when you use --prefix=/usr resulting in the includedir /usr/include:

--- SNIP ---
make[2]: Entering directory /home/gernot/xenomai/include' make[3]: Entering directory /home/gernot/xenomai/include' make[3]: Nothing to be done for `install-exec-am'. rm -f /usr/include/asm
rm: cannot remove `/usr/include/asm': Is a directory make[3]: *** [install-data-local] Error 1
--- SNAP ---

As far as I understood Jan, using /usr/include is a bad idea, so I created a patch telling the user what went wrong in a nicer way.

Please apply if you consider it to be the right fix (tm).

Gernot Hillier
Siemens AG, CT SE 2
Corporate Competence Center Embedded Linux

Index: configure.in
===================================================================
@@ -14,6 +14,10 @@
 	XENO_EMPTY_CFLAGS=false
 fi
 
+if eval test $includedir = /usr/include; then
+  AC_MSG_ERROR([Using /usr/include as includedir is not supported. Please change your --prefix or specify another --includedir])
+fi
+
 AC_CONFIG_HEADERS(src/include/xeno_config.h)
 AC_CONFIG_AUX_DIR(config)
 AC_CONFIG_SRCDIR(src/skins/native/task.c)

That makes sense, especially since that would prevent people from inadvertently trashing their local header space. People who really want to play this game should use DESTDIR explicitly instead. Merged, thanks.

Philippe.