add make distcheck

Makefile

@@ -175,6 +175,16 @@ test/misc: test/misc.c test/tests.o utf8proc.o utf8proc.h test/tests.h
 dist:
 	git archive master --prefix=utf8proc-$(VERSION)/ -o utf8proc-$(VERSION).tar.gz
 
+# build tarball, make sure it passes checks, and make sure version numbers are consistent
+distcheck: dist
+	test `grep UTF8PROC_VERSION utf8proc.h | cut -d' ' -f3 | tr '\n' .` = $(VERSION). || exit 1
+	test `grep "utf8proc VERSION" CMakeLists.txt |cut -d' ' -f 4` = $(VERSION) || exit 1
+	test `grep  libutf8proc.so.$(MAJOR).$(MINOR).$(PATCH) MANIFEST | wc -l` = 3 || exit 1
+	test `grep 'set(SO_' CMakeLists.txt |cut -d' ' -f2 | tr -d ')' | tr '\n' '.'` = $(MAJOR).$(MINOR).$(PATCH). || exit 1
+	tar xzf utf8proc-$(VERSION).tar.gz
+	make -C utf8proc-$(VERSION) check
+	rm utf8proc-$(VERSION).tar.gz
+
 check: test/normtest data/NormalizationTest.txt data/Lowercase.txt data/Uppercase.txt test/graphemetest data/GraphemeBreakTest.txt test/printproperty test/case test/iscase test/custom test/charwidth test/misc test/valid test/iterate bench/bench.c bench/util.c bench/util.h utf8proc.o
 	$(MAKE) -C bench
 	test/normtest data/NormalizationTest.txt