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/vtysh/Makefile.am b/vtysh/Makefile.am
index 850b505..d347735 100644
--- a/vtysh/Makefile.am
+++ b/vtysh/Makefile.am
@@ -5,8 +5,7 @@
 
 LIBS = @LIBS@ @CURSES@ @LIBPAM@
 
-AM_CFLAGS = $(PICFLAGS) $(WERROR)
-AM_LDFLAGS = $(PILDFLAGS)
+AM_CFLAGS = $(WERROR)
 
 bin_PROGRAMS = vtysh