quote: add sq_append_quote_argv_pretty()

sq_quote_argv_pretty() builds a "pretty" string from the given argv.
It inserts whitespace before each value, rather than just between
them, so the resulting string always has a leading space.  Lets give
callers an option to not have the leading space or have to ltrim()
it later.

Create sq_append_quote_argv_pretty() to convert an argv into a
pretty, quoted if necessary, string with space delimiters and
without a leading space.

Convert the existing sq_quote_argv_pretty() to use this new routine
while preserving the leading space behavior.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

quote.c

@@ -84,12 +84,28 @@ void sq_quote_argv(struct strbuf *dst, const char **argv)
 	}
 }
 
+/*
+ * Legacy function to append each argv value, quoted as necessasry,
+ * with whitespace before each value.  This results in a leading
+ * space in the result.
+ */
 void sq_quote_argv_pretty(struct strbuf *dst, const char **argv)
+{
+	if (argv[0])
+		strbuf_addch(dst, ' ');
+	sq_append_quote_argv_pretty(dst, argv);
+}
+
+/*
+ * Append each argv value, quoted as necessary, with whitespace between them.
+ */
+void sq_append_quote_argv_pretty(struct strbuf *dst, const char **argv)
 {
 	int i;
 
 	for (i = 0; argv[i]; i++) {
-		strbuf_addch(dst, ' ');
+		if (i > 0)
+			strbuf_addch(dst, ' ');
 		sq_quote_buf_pretty(dst, argv[i]);
 	}
 }

quote.h

@@ -40,6 +40,7 @@ void sq_quotef(struct strbuf *, const char *fmt, ...);
  */
 void sq_quote_buf_pretty(struct strbuf *, const char *src);
 void sq_quote_argv_pretty(struct strbuf *, const char **argv);
+void sq_append_quote_argv_pretty(struct strbuf *dst, const char **argv);
 
 /* This unwraps what sq_quote() produces in place, but returns
  * NULL if the input does not look like what sq_quote would have