cc/gcc: diable libsanitizer without NPTL

gcc-4.8 comes with a new library to sanitise memory access:
- heap-, stack-, and global-buffer overflow, use-after-free
- data-races between threads

This library requires some _np parts of the API, which are not
implemented in the (old) LinuxThreads, which is still available
in uClibc.

Since NPTL requires a i486 or above, i386 are stuck with using LT,
which precludes building the libsanitizer.

Disable libsanitizer, a bit like libatomic is.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Niels Penneman <niels@penneman.org>

 diff -ru ltrace-0.5.3.org/Makefile.in ltrace-0.5.3/Makefile.in

 --- ltrace-0.5.3.org/Makefile.in	2011-08-21 18:55:15.000000000 +0200

 +++ ltrace-0.5.3/Makefile.in	2011-08-21 18:40:53.000000000 +0200

 @@ -39,7 +40,7 @@

  		$(CC) $(LDFLAGS) $^ $(LIBS) -o $@

  libltrace.a: 	sysdeps/sysdep.o $(OBJ)

 -		$(AR) rcv $@ $^

 +		$(AR) rscv $@ $^

  $(OBJ):		sysdeps/sysdep.o