configure.in: Check for unistd.h as well.

�
	* configure.in: Check for unistd.h as well.
	* configure: Rebuild.
	* config.in: Rebuild.
	* getpagesize.c (GNU_OUR_PAGESIZE): Use sysconf only if _SC_PAGESIZE
	is defined in unistd.h. Reformat conditional block for easier reading.
	* config.table (shared): Default to no if ${enable_shared}
	is unset or empty; this logic is used by the toplevel
	configure scripts, too.

From-SVN: r19923

libiberty/configure.in

@@ -104,7 +104,7 @@ AC_SUBST_FILE(host_makefile_frag)
 # It's OK to check for header files.  Although the compiler may not be
 # able to link anything, it had better be able to at least compile
 # something.
-AC_CHECK_HEADERS(sys/file.h sys/param.h stdlib.h string.h)
+AC_CHECK_HEADERS(sys/file.h sys/param.h stdlib.h string.h unistd.h)
 
 # This is the list of functions which libiberty will provide if they
 # are not available on the host.