+# This converts a file name into header guard macro format.
+hg_sed_expr='y,abcdefghijklmnopqrstuvwxyz./,ABCDEFGHIJKLMNOPQRSTUVWXYZ__,'
+header_guard=GCC_`echo ${output} | sed -e ${hg_sed_expr}`
+
+# Add multiple inclusion protection guard, part one.
+echo "#ifndef ${header_guard}" >> ${output}T
+echo "#define ${header_guard}" >> ${output}T
+
+# A special test to ensure that build-time files don't blindly use
+# config.h.
+if test x"$output" = x"config.h"; then
+ echo "#ifdef GENERATOR_FILE" >> ${output}T
+ echo "#error config.h is for the host, not build, machine." >> ${output}T
+ echo "#endif" >> ${output}T
+fi
+