config: re-calculate absolute %include path in `include` callback
This removes the last user of the `abs` argument for the `include`
callback. The next patch will remove the argument.
Differential Revision: https://phab.mercurial-scm.org/D8795
CC := gcc
CFLAGS := -g -O2 -Wall -Werror
prefix ?= /usr/bin
hgsh: hgsh.o
$(CC) -o $@ $<
install: hgsh
install -m755 hgsh $(prefix)
clean:
rm -f *.o hgsh