scripts/gdb: If not building expat for gdb, disable

--with-expat=yes is unconditionally passed to the gdb configure
stage, instead of respecting the ${do_expat} decision.

Disable if not needed. Prevents error building canadian cross;

configure: error: expat is missing or unusable

Where configure stage fails to find expat on the host compiler.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
Message-Id: <4c4410a2a8aab24a29c5.1349244128@localhost.localdomain>
PatchWork-Id: 188711

 diff -Narup uClibc-0.9.30.1.orig/libc/inet/getaddrinfo.c uClibc-0.9.30.1/libc/inet/getaddrinfo.c

 --- uClibc-0.9.30.1.orig/libc/inet/getaddrinfo.c	2009-02-26 21:49:14.000000000 +0900

 +++ uClibc-0.9.30.1/libc/inet/getaddrinfo.c	2009-03-06 00:59:23.000000000 +0900

 @@ -187,6 +187,8 @@ static unsigned __check_pf(void)

  		}

  		for (runp = ifa; runp != NULL; runp = runp->ifa_next) {

 +			if (runp->ifa_addr == NULL)

 +				continue;

  #if defined __UCLIBC_HAS_IPV4__

  			if (runp->ifa_addr->sa_family == PF_INET)

  				seen |= SEEN_IPV4;