[Exim] 'make install' options

I had a need to be able to run the command 'make install eximon.bin' from
the base of the extracted exim.tgz, so I make a teensy modification to the
Makefile, along the lines of the go: line.

I doubt anyone would actually have much of a use for this, but just incase
anyone does, apply the small patch below, then run 'make IFLAGS="eximon.bin"
install'.

             "If you wanna find me, I'll be out in the sandbox..."
                                                  Barenaked Ladies

--- Makefile.orig       Wed Aug 15 12:09:05 2001
+++ Makefile
@@ -65,7 +65,7 @@
 # The installation commands are kept in a separate script, which expects
 # to be run from inside the build directory.

-install:;      @cd build-$(buildname); $(SHELL) ../scripts/exim_install
+install:;      @cd build-$(buildname); $(SHELL) ../scripts/exim_install $(IFLAGS)

# Tidy-up targets