Allow LDFLAGS to be passed from the environment.
--- configure.orig 2017-10-26 04:00:30.000000000 -0500
+++ configure 2018-02-22 15:15:10.000000000 -0600
#----------------------------------------------------------------------
# Initialize all variables here such that nothing can leak in from the
-# environment except for CC and CFLAGS, which we might have passed in.
+# environment except for CC, CFLAGS and LDFLAGS, which we might have passed in.
#----------------------------------------------------------------------
CC=`printf "all:\\n\\t@echo \\\$(CC)\\n" | make -sf -`
CFLAGS="${CFLAGS} -Wwrite-strings -Wno-unused-parameter"
+LDFLAGS=`printf "all:\\n\\t@echo \\\$(LDFLAGS)\\n" | make -sf -`