lib: undo the last PIE commit

Stephen:
A recent change breaks build Quagga on Debian Lenny with amd64 (but not
i386). Not sure whether this is cause by ld, gcc, or libtool; but
whatever it just won't work for a large number of users.

Mathias:
I would guess it's a problem of libtool because it adds "-fPIC -DPIC" to
the compiler flags but doesn't remove -fPIE. That wouldn't be a problem
if the compiler would ignore the -fPIE in favor to the latter -fPIC, but
obviously it does not. [...] Those objects were actually compiled with
-fPIC but also -fPIE which seems to confuse gcc.

lib/Makefile.am

@@ -14,9 +14,6 @@ libzebra_la_SOURCES = \
 	zclient.c sockopt.c smux.c md5.c if_rmap.c keychain.c privs.c \
 	sigevent.c pqueue.c jhash.c memtypes.c workqueue.c
 
-AM_CFLAGS = $(PICFLAGS)
-AM_LDFLAGS = $(PILDFLAGS)
-
 BUILT_SOURCES = memtypes.h route_types.h
 
 libzebra_la_DEPENDENCIES = @LIB_REGEX@