debian: reenable -Werror, mentioned warning already fixed

patches.debian/qrexec_disable_all_warnings_as_errors.patch

@@ -1,19 +0,0 @@
-qrexec: Disable all warnings being treated as errors
-
-gcc -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -I. -g -Wall -Wextra -Werror -pie -fPIC `pkg-config --cflags vchan-xen` -D_FORTIFY_SOURCE=2  -c -o qrexec-agent-data.o qrexec-agent-data.c
-qrexec-agent-data.c: In function 'handle_remote_data':
-qrexec-agent-data.c:217:17: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
-                 status = *(unsigned int *)buf;
-                 ^
-cc1: all warnings being treated as errors
-<builtin>: recipe for target 'qrexec-agent-data.o' failed
-
---- a/qrexec/Makefile
-+++ b/qrexec/Makefile
-@@ -1,5 +1,5 @@
- CC=gcc
--CFLAGS+=-I. -g -Wall -Wextra -Werror -pie -fPIC `pkg-config --cflags vchan-$(BACKEND_VMM)`
-+CFLAGS+=-I. -g -Wall -Wextra -pie -fPIC `pkg-config --cflags vchan-$(BACKEND_VMM)`
- LIBS=`pkg-config --libs vchan-$(BACKEND_VMM)` -lqrexec-utils
- 
- all: qrexec-agent qrexec-client-vm