ppp: fix building pptp plugin

The pptp.so plugin needs to be built with -fPIC as well in order to be
linkable again.

Fixes 888a15ff83 ("ppp: add missing -fPIC to rp-pppoe.so CFLAGS")
Fixes e7397eef69 ("ppp: compile with LTO enabled")
Signed-off-by: Jo-Philipp Wich <[email protected]>

package/network/services/ppp/Makefile

@@ -10,7 +10,7 @@ include $(INCLUDE_DIR)/kernel.mk
 
 PKG_NAME:=ppp
 PKG_VERSION:=2.4.7
-PKG_RELEASE:=12
+PKG_RELEASE:=13
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://download.samba.org/pub/ppp/

package/network/services/ppp/patches/511-pptp_cflags.patch

@@ -0,0 +1,11 @@
+--- a/pppd/plugins/pptp/Makefile.linux
++++ b/pppd/plugins/pptp/Makefile.linux
+@@ -20,7 +20,7 @@ all: pptp.so
+ 	$(CC) $(CFLAGS) -c -o $@ $<
+ 
+ pptp.so: dirutil.o orckit_quirks.o pptp.o pptp_callmgr.o pptp_ctrl.o pptp_quirks.o util.o vector.o
+-	$(CC) -o pptp.so -shared dirutil.o orckit_quirks.o pptp.o pptp_callmgr.o pptp_ctrl.o pptp_quirks.o util.o vector.o
++	$(CC) -fPIC -o pptp.so -shared dirutil.o orckit_quirks.o pptp.o pptp_callmgr.o pptp_ctrl.o pptp_quirks.o util.o vector.o
+ 
+ install: all
+ 	$(INSTALL) -d -m 755 $(LIBDIR)