rename libc to libjehanne; improve libposix

This is to avoid conflicts between standards' assumptions and Jehanne's choices

sys/src/lib/jehanne/port/toupper.c

@@ -0,0 +1,28 @@
+/*
+ * This file is part of the UCB release of Plan 9. It is subject to the license
+ * terms in the LICENSE file found in the top-level directory of this
+ * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
+ * part of the UCB release of Plan 9, including this file, may be copied,
+ * modified, propagated, or distributed except according to the terms contained
+ * in the LICENSE file.
+ */
+
+#include	<ctype.h>
+
+int
+jehanne_toupper(int c)
+{
+
+	if(c < 'a' || c > 'z')
+		return c;
+	return _toupper(c);
+}
+
+int
+jehanne_tolower(int c)
+{
+
+	if(c < 'A' || c > 'Z')
+		return c;
+	return _tolower(c);
+}