contrib/hgsh/Makefile

extdiff: remove dir2root and pass full path as dir2 in _runperfilediff()

The only use of `dir2root` was to join with `dir2` to generate the path for
other side of diff. Like in previous patch, `dir1a` and `dir1b` are full paths
and no longer base names, hence we pass `dir2` as full path too and making
`dir2root` unrequired.

Differential Revision: https://phab.mercurial-scm.org/D8970

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