make install puts ocamlc at workspace root (#152)

This `ocamlc` is nicer to use with `ocamldebug`, as
the `ocamldebug` session inherits the pwd of the bytecode
file you pass as argument. In particular, breakpoints bring
you to the proper file if you use the root `ocamlc`, and
bring you to the copied file in the `_build` directory if
you use the `$USER-out/bin/` `ocamlc`.

Author: ncik-roberts

Makefile.common-jst

@@ -166,10 +166,16 @@ _install: compiler
           -or -name "flambda2*.cmti" -or -name "flambda2*.cmt" \) \
           -exec cp -f {} _install/lib/ocaml/compiler-libs \;
 
-# Copy _install to the final install directory (no-op if they are the same)
+# Copy _install to the final install directory (no-op if they are the same).
+# Also generate ocamlc at the root of the repo, as this is convenient to use
+# with ocamldebug: ocamldebug inherits the pwd of the file passed as argument,
+# so breakpoints bring you to the less-convenient _build source file if you use
+# the ocamlc.byte in $prefix/bin.
 install: _install
 	mkdir -p '$(prefix)'
 	rsync --chmod=u+rw,go+r -rl _install/ '$(prefix)'
+	rm -f ocamlc
+	ln -s '$(prefix)'/bin/ocamlc.byte ocamlc
 
 # Same as above, but relies on a successfull earlier _install
 install_for_opam: