lib/functions.in: introduce configcachefile variable which holds a space delimited list of config.cache files

doc/PKG-BUILD-VARS

@@ -78,6 +78,7 @@ autogen ....... set to '1' if you want to run the autogen script
 confopt ....... options for GNU autoconf './configure'
 extraconfopt .. options which should be appended to $confopt by set_confopt()
 configcache ... an space delimited list of declarations for config.cache
+configcachefile an space delimited list of config.cache files
 configprefix .. variable declarations only for GNU autoconf './configure'
 configscript .. script file name of the GNU autoconf configure script
 cleanconfopt .. set to '0' if you don't want to remove unsupported options

lib/functions.in

@@ -337,6 +337,18 @@ function eval_config_command() {
 			create_config_cache >> $config_cache
 		fi
 
+		if [ -n "$configcachefile" ]; then
+			for x in $configcachefile; do
+				if [ -e $x ]; then
+					cat <<-EOT
+
+					# cache file: $x
+					EOT
+					cat "$x"
+				fi
+			done
+		fi >> $config_cache
+
 		if [ -n "$configcache" ]; then
 			cat <<-EOT