Functions to quote and unquote pathnames in C-style.

Following the list discussion, define two functions, quote_c_style and
unquote_c_style, to help adopting the proposed way for quoting funny
pathname letters for GNU patch.  The rule is described in:

    http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2

Currently we do not support the leading '!', but we probably should
barf upon seeing it.  Rule B4. is interpreted to require always 3
octal digits in \XYZ notation.

Signed-off-by: Junio C Hamano <junkio@cox.net>

quote.h

@@ -2,6 +2,7 @@
 #define QUOTE_H
 
 #include <stddef.h>
+#include <stdio.h>
 
 /* Help to copy the thing properly quoted for the shell safety.
  * any single quote is replaced with '\'', any exclamation point
@@ -27,7 +28,14 @@
  * excluding the final null regardless of the buffer size.
  */
 
-char *sq_quote(const char *src);
-size_t sq_quote_buf(char *dst, size_t n, const char *src);
+extern char *sq_quote(const char *src);
+extern size_t sq_quote_buf(char *dst, size_t n, const char *src);
+
+extern int quote_c_style(const char *name, char *outbuf, FILE *outfp,
+			 int nodq);
+extern char *unquote_c_style(const char *quoted, const char **endp);
+
+extern void write_name_quoted(const char *prefix, const char *name,
+			      int quote, FILE *out);
 
 #endif