configure.in (--enable-c-cpplib): New option.

* configure.in (--enable-c-cpplib):  New option.
(extra_c_flags, extra_c_objs):  New variables.

From-SVN: r14556

gcc/configure.in

@@ -79,6 +79,14 @@ if [[ x$gxx_include_dir = x ]]; then
 	gxx_include_dir='${prefix}/include/g++'
 fi
 
+# Enable use of cpplib for C.
+AC_ARG_ENABLE(c-cpplib,
+[  --enable-c-cpplib       Use cpplib for C.],
+if [[[ x$enable_c_cpplib != xno ]]]; then
+  extra_c_objs="${extra_c_objs} cpplib.o cppexp.o cpphash.o cpperror.o"
+  extra_c_flags=-DUSE_CPPLIB=1
+fi)
+
 # Enable threads
 # Pass with no value to take the default
 # Pass with a value to specify a thread package
@@ -3016,6 +3024,8 @@ AC_SUBST(all_headers)
 AC_SUBST(extra_passes)
 AC_SUBST(extra_programs)
 AC_SUBST(extra_parts)
+AC_SUBST(extra_c_objs)
+AC_SUBST(extra_c_flags)
 AC_SUBST(extra_objs)
 AC_SUBST(host_extra_gcc_objs)
 AC_SUBST(extra_headers_list)