nroff: fix two syntax mistakes

ares_parse_a_reply and ares_parse_aaaa_reply both had two \fB instead of
\fP

Reported-by: Alexander Klauer
Bug: http://c-ares.haxx.se/mail/c-ares-archive-2013-03/0010.shtml

ares_parse_a_reply.3

@@ -22,7 +22,7 @@ ares_parse_a_reply \- Parse a reply to a DNS query of type A
 .PP
 .B int ares_parse_a_reply(const unsigned char *\fIabuf\fP, int \fIalen\fP,
 .B 	struct hostent **\fIhost\fP,
-.B      struct ares_addrttl *\fIaddrttls\fB, int *\fInaddrttls\fB);
+.B      struct ares_addrttl *\fIaddrttls\fP, int *\fInaddrttls\fP);
 .fi
 .SH DESCRIPTION
 The

ares_parse_aaaa_reply.3

@@ -22,7 +22,7 @@ ares_parse_aaaa_reply \- Parse a reply to a DNS query of type AAAA
 .PP
 .B int ares_parse_aaaa_reply(const unsigned char *\fIabuf\fP, int \fIalen\fP,
 .B 	struct hostent **\fIhost\fP,         
-.B      struct ares_addr6ttl *\fIaddrttls\fB, int *\fInaddrttls\fB);
+.B      struct ares_addr6ttl *\fIaddrttls\fP, int *\fInaddrttls\fP);
 .fi
 .SH DESCRIPTION
 The