Fix buffer overflow in config parser

When interpreting a config value, the config parser reads in 1+ space
character(s) and puts -one- space character in the buffer as soon as
the first non-space character is encountered (if not inside quotes).

Unfortunately the buffer size check lacks the extra space character
which gets inserted at the next non-space character, resulting in
a crash with a specially crafted config entry.

The unit test now uses Java to compile a platform independent
.NET framework to output the test string in C# :o)

    Read: Thanks to Johannes Sixt for the correct printf call
    which replaces the perl invocation.

Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -51,7 +51,7 @@ static char *parse_value(void)
 
 	for (;;) {
 		int c = get_next_char();
-		if (len >= sizeof(value))
+		if (len >= sizeof(value) - 1)
 			return NULL;
 		if (c == '\n') {
 			if (quote)