build: Remove the old PIC/PIE patch, let libtool sort it out

* Remove the old change from '08 to add in PIE arguments at automake level.
  Versions of libtool since then know how to deal with -fpie and do the right
  thing according to whether its building shared or executable objects.
  So just pass '-fpie' as CFLAG and let libtool do its thing.
diff --git a/bgpd/Makefile.am b/bgpd/Makefile.am
index 92fa10c..4659ac6 100644
--- a/bgpd/Makefile.am
+++ b/bgpd/Makefile.am
@@ -4,8 +4,7 @@
 DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\"
 INSTALL_SDATA=@INSTALL@ -m 600
 
-AM_CFLAGS = $(PICFLAGS) $(WERROR)
-AM_LDFLAGS = $(PILDFLAGS)
+AM_CFLAGS = $(WERROR)
 
 noinst_LIBRARIES = libbgp.a
 sbin_PROGRAMS = bgpd