+export IS_TTY=$(shell tty -s && echo 1 || echo 0)
+export LD_LIBRARY_PATH:=$(if $(LD_LIBRARY_PATH),$(LD_LIBRARY_PATH):)$(STAGING_DIR_HOST)/lib
+export DYLD_LIBRARY_PATH:=$(if $(DYLD_LIBRARY_PATH),$(DYLD_LIBRARY_PATH):)$(STAGING_DIR_HOST)/lib
+
+# prevent perforce from messing with the patch utility
+unexport P4PORT P4USER P4CONFIG P4CLIENT
+
+# prevent user defaults for quilt from interfering
+unexport QUILT_PATCHES QUILT_PATCH_OPTS
+
+unexport C_INCLUDE_PATH
+
+# prevent distro default LPATH from interfering
+unexport LPATH
+
+# make sure that a predefined CFLAGS variable does not disturb packages
+export CFLAGS=