RFC: USE_LLD=No for default-is-lld arches

Not sure if this is useful or unnecessary bloat, it provides a way to switch
back to ld.bfd on arches which default to ld.lld to switch back to ld.bfd.
(It hasn't gone into a bulk yet). Thoughts?


Index: bsd.port.mk
===================================================================
RCS file: /cvs/ports/infrastructure/mk/bsd.port.mk,v
retrieving revision 1.1450
diff -u -p -r1.1450 bsd.port.mk
--- bsd.port.mk 18 Oct 2018 09:38:32 -0000 1.1450
+++ bsd.port.mk 30 Oct 2018 11:52:03 -0000
@@ -392,12 +392,6 @@ BASELOCALSTATEDIR ?= ${VARBASE}
LOCALSTATEDIR ?= ${BASELOCALSTATEDIR}

RCDIR ?= /etc/rc.d
-USE_LLD ?= No
-.if ${USE_LLD:L} == "yes"
-_LD_PROGRAM = /usr/bin/ld.lld
-.else
-_LD_PROGRAM = /usr/bin/ld
-.endif
USE_WXNEEDED ?= No
.if ${USE_WXNEEDED:L} == "yes"
_WXNEEDED_FLAGS = -z wxneeded
@@ -795,6 +789,30 @@ CONFIGURE_ENV += ${_EXTRA_ENV}
MAKE_ENV += ${_EXTRA_ENV}
.endif

+.if ${PROPERTIES:Mlld}
+USE_LLD ?= Yes
+.else
+USE_LLD ?= No
+.endif
+
+.if ${USE_LLD:L} == "yes"
+_LD_PROGRAM = /usr/bin/ld.lld
+. if ! ${PROPERTIES:Mlld}
+_NONDEFAULT_LD = Yes
+. endif
+.else
+_LD_PROGRAM = /usr/bin/ld.bfd
+. if ${PROPERTIES:Mlld}
+_NONDEFAULT_LD = Yes
+. endif
+.endif
+
+.if ${_LD_PROGRAM} != ${_LD_DEFAULT}
+_NONDEFAULT_LD = Yes
+.else
+_NONDEFAULT_LD = No
+.endif
+
# setup locations of compilers from the base system or environment variables.
# MODULES for compilers (gcc4.port.mk, clang.port.mk) also append to this,
# used to write wrappers to WRKDIR/bin which is at the head of the PATH.
@@ -2667,7 +2685,7 @@ ${_PATCH_COOKIE}: ${_EXTRACT_COOKIE}

# Run as _pbuild
_post-patch-finalize:
-.if ${USE_WXNEEDED:L} == "yes" || ${USE_LLD:L} == "yes"
+.if ${USE_WXNEEDED:L} == "yes" || ${_NONDEFAULT_LD:L} == "yes"
@wrktmp=`df -P ${WRKOBJDIR_${PKGPATH}} | awk 'END { print $$6 }'`; \
if ! mount | grep -q " $${wrktmp} .*wxallowed"; then \
echo "Fatal: ${WRKOBJDIR_${PKGPATH}} must be on a wxallowed filesystem" \