Makefile: Add BINTOPKGLIBEXECDIR macro.

Makefile

@@ -144,9 +144,10 @@ WIRE_GEN := tools/generate-wire.py
 
 ALL_PROGRAMS =
 
+CPPFLAGS = -DBINTOPKGLIBEXECDIR='"'$(shell sh tools/rel.sh $(bindir) $(pkglibexecdir))'"'
 CWARNFLAGS := -Werror -Wall -Wundef -Wmissing-prototypes -Wmissing-declarations -Wstrict-prototypes -Wold-style-definition
 CDEBUGFLAGS := -std=gnu11 -g -fstack-protector
-CFLAGS = $(CWARNFLAGS) $(CDEBUGFLAGS) -I $(CCANDIR) $(EXTERNAL_INCLUDE_FLAGS) -I . $(FEATURES) $(COVFLAGS) $(DEV_CFLAGS) -DSHACHAIN_BITS=48
+CFLAGS = $(CPPFLAGS) $(CWARNFLAGS) $(CDEBUGFLAGS) -I $(CCANDIR) $(EXTERNAL_INCLUDE_FLAGS) -I . $(FEATURES) $(COVFLAGS) $(DEV_CFLAGS) -DSHACHAIN_BITS=48
 
 LDLIBS = -lgmp -lsqlite3 $(COVFLAGS)
 
@@ -311,6 +312,7 @@ prefix = /usr/local
 exec_prefix = $(prefix)
 bindir = $(exec_prefix)/bin
 libexecdir = $(exec_prefix)/libexec
+pkglibexecdir = $(libexecdir)/$(PKGNAME)
 datadir = $(prefix)/share
 docdir = $(datadir)/doc/$(PKGNAME)
 mandir = $(datadir)/man

tools/rel.sh

@@ -0,0 +1,7 @@
+#! /bin/sh
+
+from=${1}
+to=${2}
+common=`printf '%s\0%s' "${from}" "${to}" | sed 's/\(.*\).*\x0\1.*/\1/' | sed 's@/[^/]*$@/@'`
+prefix=`printf '%s\n' ${from#$common} | sed 's@[^/][^/]*@..@g'`
+printf '%s\n' "$prefix/${to#$common}"