Add support for "\a" and "\v" to regex and command line args (#44)

Support POSIX-specified C-style escape sequences "\a" (alarm)
and "\v" (vertical tab) in command line arguments and regular
expressions, further to the support for them in strings added on
Apr 9, 1989. These now no longer match as literal "a" and "v"
characters (as they don't on gawk and mawk).

IOW, lex.c already supported these (lines 390-391 as of 4e343460);
the support needed to be added to b.c and tran.c.

Relevant POSIX reference:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html#tag_20_06_13_04

1 files changed, 4 insertions, 0 deletions

diff --git a/b.c b/b.c
index 3f6745c..91dd78d 100644
--- a/b.c
+++ b/b.c
@@ -279,6 +279,10 @@ int quoted(uschar **pp)	/* pick up next thing after a \\ */
 		c = '\r';
 	else if (c == 'b')
 		c = '\b';
+	else if (c == 'v')
+		c = '\v';
+	else if (c == 'a')
+		c = '\a';
 	else if (c == '\\')
 		c = '\\';
 	else if (c == 'x') {	/* hexadecimal goo follows */