build: drop config.log in favor of reconfigure

The configure command line is now turned into an
executable script called reconfigure which can be invoked to
repeat the config.

* Makefile (distclean): Whether in a configured or state or
not, try to remove reconfigure. In the configured state, don't
remove config.log. (If distclean is invoked when not
configured, the config.* pattern will remove config.log).

* configure: rewrite the logic which turns the command line
into text. It is now robust against spaces, quotes and
meta-charaters. Moreover, the printed representation is chosen
according to good heuristics to minimize unnecessary quoting
and escaping. The config line is written into an executable
script called reconfigure. This is now done twice; it is done
immediately, so that we save the command line even if the
configure subsequently fails. A comment is added to
reconfigure indicating that configure didn't succeed. Then
after a successful run through the tests, we save it again,
without the cautionary comment. Help texts updated.

1 files changed, 2 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 66fae7b3..eef7f722 100644
--- a/Makefile
+++ b/Makefile
@@ -346,7 +346,7 @@ distclean:
 	rm -f txr txr.exe txr-dbg txr-dbg.exe txr-win.exe txr-win-dbg.exe
 	rm -rf y.tab.c lex.yy.c y.tab.h y.output
 	rm -rf config opt dbg share/txr/stdlib/*.tlo* run.sh
-	rm -f config.*
+	rm -f config.* reconfigure
 	rm -rf mpi-1.?.?
 else
 rebuild: clean repatch $(PROG)
@@ -361,7 +361,7 @@ clean-tlo:
 	rm -f $(STDLIB_TLOS)
 
 distclean: clean
-	rm -f config.h config.make config.log
+	rm -f config.h config.make reconfigure
 endif
 
 TESTS_OK := $(addprefix tst/,\