Drop no-pie-on-ubuntu tweak in postgis?

[Christoph Berg]

We have decent test coverage now, can we drop this bit in postgis?

# Disable PIE on Ubuntu where it's still problematic
VENDOR_DERIVES_FROM_UBUNTU ?= $(shell dpkg-vendor --derives-from Ubuntu && echo yes)
DISTRIBUTION_RELEASE       := $(shell lsb_release -cs)

ifeq ($(VENDOR_DERIVES_FROM_UBUNTU),yes)
  ifneq (,$(filter $(DISTRIBUTION_RELEASE),trusty xenial bionic))
    export DEB_BUILD_MAINT_OPTIONS=hardening=+all,-pie
  endif
endif

Christoph