Add --config option printing ./configure options used

Makefile.am

@@ -33,12 +33,12 @@ ACLOCAL_AMFLAGS = -I config/m4
 # header file creation so we'll use good old make
 if MAINTAINER_MODE
 BUILT_SOURCES = src/lexer.h src/lexer.c src/parser.h src/parser.c 	\
-		src/builtin.inc src/version.h
+		src/builtin.inc src/config_opts.inc src/version.h
 src/lexer.c: src/lexer.l
 	$(AM_V_LEX) flex -o src/lexer.c --header-file=src/lexer.h $<
 src/lexer.h: src/lexer.c
 else
-BUILT_SOURCES = src/builtin.inc src/version.h
+BUILT_SOURCES = src/builtin.inc src/config_opts.inc src/version.h
 .y.c:
 	$(AM_V_YACC) echo "NOT building parser.c!"
 .l.c:
@@ -109,14 +109,20 @@ generate_ver = ver="`{ $(srcdir)/scripts/version || echo '$(VERSION)' ; } | sed
 src/version.h: .remake-version-h
 	mkdir -p src
 	$(AM_V_GEN) $(generate_ver); echo "$$ver" > $@
-src/main.c: src/version.h
+src/config_opts.inc:
+	mkdir -p src
+	$(AM_V_GEN) if test -x ./config.status; then \
+	  ./config.status --config; \
+	else echo "(unknown)"; \
+	fi | sed -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e 's/^/"/' -e 's/$$/"/' -e 's/^/#define JQ_CONFIG /' > $@
+src/main.c: src/version.h src/config_opts.inc
 
 src/builtin.inc: $(srcdir)/src/builtin.jq
 	mkdir -p src
 	$(AM_V_GEN) sed -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e 's/^/"/' -e 's/$$/\\n"/' $(srcdir)/src/builtin.jq > $@
 src/builtin.o: src/builtin.inc
 
-CLEANFILES = src/version.h .remake-version-h src/builtin.inc
+CLEANFILES = src/version.h .remake-version-h src/builtin.inc src/config_opts.inc
 
 bin_PROGRAMS = jq
 jq_SOURCES = src/main.c src/version.h