Tapeutils doesn't build with Cygwin

[jfcl]

Simple obvious fix attached.

$ git diff -u read20.c
diff --git a/read20.c b/read20.c
index 92ee00a..b152bf7 100644
--- a/read20.c
+++ b/read20.c
@@ -86,7 +86,7 @@ char *expression = 0;
 char *re_comp_error;     /* Error message from re_comp() */
 extern char *re_comp();

-#if defined(__APPLE__) || defined(__OpenBSD__)
+#if defined(__APPLE__) || defined(__OpenBSD__) || defined(__CYGWIN__)
 static regex_t re_regexp;

 char *re_comp(char *s)
            

[jfcl]

Submitted pull request https://github.com/brouhaha/tapeutils/pull/14

[larsbrinkhoff]

Merged; thanks!