Try to get ride of LDFLAGS on xUbuntu

Ubuntu compiles the shared libs with

-Wl,-Bsymbolic-functions -Wl,-z,relro

which makes the config_engine blowup as function pointers are not ok
and all offsets calculated at compile time are not right and as such
the whole config structure doesn't get initialized properly and the code
crashes at random places.

debian/rules

@@ -16,10 +16,7 @@ export DH_VERBOSE=1
 # This has to be exported to make some magic below work.
 export DH_OPTIONS=-v
 
-#export DEB_BUILD_OPTIONS=noopt
-#export DEB_CFLAGS_MAINT_APPEND=-O0
-export CFLAGS=-g -O0
-export CXXFLAGS=-g -O0
+export LDFLAGS=""
 
 export daemon_user=bareos
 export daemon_group=bareos