add and apply debian_hardening_flags.patch

Makefile

@@ -564,6 +564,7 @@ config.mak: Makefile.defs
 	@echo "# this file is autogenerated by make cfg" >$@
 	@$(call mapf2,cfg_save_var,saved_fixed_vars,$(@))
 	@$(call mapf2,cfg_save_var2,saved_chg_vars,$(@))
+	@echo "CFLAGS += $(CPPFLAGS)" >>$@
 	@echo "override makefile_defs:=1" >>$@
 	@echo "C_DEFS:=\$$(filter-out \$$(DEFS_RM) \$$(extra_defs),\$$(C_DEFS))" \
 					"\$$(extra_defs)"  >>$@

Makefile.defs

@@ -858,8 +858,6 @@ ifeq ($(use_fast_lock), yes)
 	found_lock_method=yes
 endif
 
-CFLAGS=
-LDFLAGS=
 C_INCLUDES=
 # setting CFLAGS
 ifeq ($(mode), release)

sipwise_patches/debian_hardening_flags.patch

@@ -0,0 +1,28 @@
+Description: Do pass hardening {C,CPP,LD}FLAGS
+Author: Tzafrir Cohen <tzafrir@debian.org>
+
+Make sure that the *FLAGS variables set by dpkg-buildflags make it to kamailio:
+* add CPPFLAGS to CFLAGS
+* Don't reset CFLAGS and LDFLAGS
+
+--- a/Makefile.defs
++++ b/Makefile.defs
+@@ -855,8 +855,6 @@ ifeq ($(use_fast_lock), yes)
+ 	found_lock_method=yes
+ endif
+ 
+-CFLAGS=
+-LDFLAGS=
+ C_INCLUDES=
+ # setting CFLAGS
+ ifeq ($(mode), release)
+--- a/Makefile
++++ b/Makefile
+@@ -563,6 +563,7 @@ config.mak: Makefile.defs
+ 	@echo "# this file is autogenerated by make cfg" >$@
+ 	@$(call mapf2,cfg_save_var,saved_fixed_vars,$(@))
+ 	@$(call mapf2,cfg_save_var2,saved_chg_vars,$(@))
++	@echo "CFLAGS += $(CPPFLAGS)" >>$@
+ 	@echo "override makefile_defs:=1" >>$@
+ 	@echo "C_DEFS:=\$$(filter-out \$$(DEFS_RM) \$$(extra_defs),\$$(C_DEFS))" \
+ 					"\$$(extra_defs)"  >>$@