edify_generator.py: Reconcile symlink wordwrapping w/ cm

Change-Id: Id1c771a1b7beb3176a97b1396b39f90e6656625b
Revert "Allow devices to specify certain ro. props via TARGET_UNIFIED_DEVICE"

This reverts commit 3713520983b785d1eba85a27eb1a588d38aab7d5.
Allow complete opt out of per-arch toolchains with TARGET_KERNEL_USE_AOSP_TOOLCHAIN:=true

Change-Id: Ifa44fc2f8200ab6a9e47575e2e5a4220da7c2702
build: give CPPFLAGS some love, and make FPU  handling smarter for non-vanirified device trees

"FPU"? more like "FSU" - BEEYAWWW

ps1: firsties
ps2: handle determined cflags in TARGET_linux-arm, like -mcpu, etc. are handled
ps3: remove a $(warning ...) added for debugging
     use target_arch_variant_cflags for TARGET_GLOBAL_CPPFLAGS too (has -mcpu, -march, in addition to fpu stuff)
     remove stuff related to arch_variant_cppflags, which was just "arch_variant_cflags with less hotsauce"

Change-Id: Ic8dc75af2c18375dcf69046d48d9ff84dbffb7f0