Fix phpdbg prompt with editline/readline integration

When building phpdbg SAPI with libedit/readline integration, also start
and end ignore characters need to be added in the prompt pattern. This
should work now for libedit, readline, and phpdbg without
readline/libedit.

The RL_PROMPT_START_IGNORE and RL_PROMPT_END_IGNORE macros are checked
there to ensure libedit has these available. Otherwise, this could be
further improved by concatenating strings and literal strings into
single argument or similar using these two symbols directly.

Autotools:

    ./configure --with-libedit --enable-phpdbg-readline
    make
    ./sapi/phpdbg/phpdb

In the phpdbg, the "prompt" should be colored (or bold) in some
terminals.

Author: petk

sapi/phpdbg/phpdbg_utils.c

@@ -318,10 +318,14 @@ PHPDBG_API const char *phpdbg_get_prompt(void) /* {{{ */
 	}
 
 	/* create cached prompt */
-#ifndef HAVE_LIBEDIT
-	/* TODO: libedit doesn't seems to support coloured prompt */
+#if !defined(HAVE_LIBEDIT) || (defined(HAVE_LIBEDIT) && defined(RL_PROMPT_START_IGNORE) && defined(RL_PROMPT_END_IGNORE))
 	if ((PHPDBG_G(flags) & PHPDBG_IS_COLOURED)) {
-		ZEND_IGNORE_VALUE(asprintf(&PHPDBG_G(prompt)[1], "\033[%sm%s\033[0m ",
+		ZEND_IGNORE_VALUE(asprintf(&PHPDBG_G(prompt)[1],
+# if defined(HAVE_LIBEDIT) && defined(RL_PROMPT_START_IGNORE) && defined(RL_PROMPT_END_IGNORE)
+			"\1\033[%sm\2%s\1\033[0m\2 ",
+# else
+			"\033[%sm%s\033[0m ",
+# endif
 			PHPDBG_G(colors)[PHPDBG_COLOR_PROMPT]->code,
 			PHPDBG_G(prompt)[0]));
 	} else