Use MacPorts CFLAGS.
--- configure.orig	2014-08-11 14:14:36.000000000 -0500
+++ configure	2022-08-20 23:51:43.000000000 -0500
@@ -870,6 +870,7 @@
 		V_CCOPT="-O2"
 	fi
 fi
+V_CCOPT="$CFLAGS"
 if test -f .devel ; then
 	V_CCOPT="-g $V_CCOPT -ansi -pedantic -U__STRICT_ANSI__ -Wall -Wpointer-arith -Wshadow -Wcast-qual -Wcast-align -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wredundant-decls -Wno-long-long"
 fi