scripts: fix sysroot prefix dir

The sysroot prefix dir was broken in #4960f5d9f829 due to a mishap
when making the out-of-sysroot lib/ symlink: the './' was mistakenly
changed into a single '.' .

Although Jonathan suggested restoring the missing '/' to restore it to
normal operation, I prefered using an explicit pushd/popd to be extra
sure of the symlink location and target, along with a fix in the sysroot
relative directory calculation.

Reported-by: Jonathan Grundon <JGrundon@xos.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from e5fc5c9ea78af28d05244ba09cf718cf75470903)

diff -durN glibc-cvs-2.9.orig/misc/syslog.c glibc-cvs-2.9/misc/syslog.c

--- glibc-cvs-2.9.orig/misc/syslog.c	2009-06-01 10:16:50.000000000 +0200

+++ glibc-cvs-2.9/misc/syslog.c	2009-06-01 10:17:20.000000000 +0200

@@ -152,7 +152,7 @@

 #define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID

 	/* Check for invalid bits. */

 	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {

-		syslog(INTERNALLOG,

+		__syslog(INTERNALLOG,

 		    "syslog: unknown facility/priority: %x", pri);

 		pri &= LOG_PRIMASK|LOG_FACMASK;

 	}