[OCaml] Use $CAMLORIGIN, an rpath-$ORIGIN-like mechanism in OCaml.

As a result, installations of LLVM in non-standard locations
will not require passing custom -ccopt -L flags when building
the binary, nor absolute paths would be embedded in the cma/cmxa
files. Additionally, the executables will not require changes
to LD_LIBRARY_PATH, although CAML_LD_LIBRARY_PATH still
has to be set for ocamlc without -custom.

See http://caml.inria.fr/mantis/view.php?id=6642.
Note that the patch is approved, but not merged yet.
It will be released in 4.03 and likely 4.02.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225778 91177308-0d34-0410-b5e6-96231b3b80d8

bindings/ocaml/Makefile.ocaml

@@ -65,6 +65,10 @@ OCAMLRPATH     := $(RPATH) -Wl,'$$ORIGIN/../../lib'
 endif
 endif
 
+# See http://caml.inria.fr/mantis/view.php?id=6642
+OCAMLORIGIN    := -ccopt -L'$$CAMLORIGIN/..' \
+                  -ccopt $(RPATH) -ccopt -Wl,'$$CAMLORIGIN/..'
+
 # Tools
 OCAMLCFLAGS += -I $(OcamlDir) $(addprefix -package ,$(FindlibPackages))
 
@@ -92,16 +96,18 @@ Compile.CMX  := $(strip $(OCAMLFIND) opt -c $(OCAMLCFLAGS) $(OCAMLDEBUGFLAG) -o)
 ifdef OCAMLSTUBS
 # -dllib is engaged with ocamlc builds, $(OCAMLSTUBFLAGS) in ocamlc -custom builds.
 Archive.CMA  := $(strip $(OCAMLFIND) c -a -dllib -l$(LIBRARYNAME) $(OCAMLSTUBFLAGS) \
-																			 $(OCAMLDEBUGFLAG) -o)
+																			 $(OCAMLDEBUGFLAG) $(OCAMLORIGIN) -o)
 else
 Archive.CMA  := $(strip $(OCAMLFIND) c -a -custom $(OCAMLAFLAGS) $(OCAMLDEBUGFLAG) \
-                                       -o)
+                                       $(OCAMLORIGIN) -o)
 endif
 
 ifdef OCAMLSTUBS
-Archive.CMXA := $(strip $(OCAMLFIND) opt -a $(OCAMLSTUBFLAGS) $(OCAMLDEBUGFLAG) -o)
+Archive.CMXA := $(strip $(OCAMLFIND) opt -a $(OCAMLSTUBFLAGS) $(OCAMLDEBUGFLAG) \
+                                         $(OCAMLORIGIN) -o)
 else
-Archive.CMXA := $(strip $(OCAMLFIND) opt -a $(OCAMLAFLAGS) $(OCAMLDEBUGFLAG) -o)
+Archive.CMXA := $(strip $(OCAMLFIND) opt -a $(OCAMLAFLAGS) $(OCAMLDEBUGFLAG) \
+                                         $(OCAMLORIGIN) -o)
 endif
 
 # Source files

cmake/modules/AddOCaml.cmake

@@ -53,6 +53,8 @@ function(add_ocaml_library name)
   endif()
 
   set(ocaml_flags "-lstdc++" "-ldopt" "-L${LLVM_LIBRARY_DIR}"
+                  "-ccopt" "-L\\$CAMLORIGIN/.."
+                  "-ccopt" "-Wl,-rpath,\\$CAMLORIGIN/.."
                   ${ocaml_pkgs})
 
   foreach( ocaml_dep ${ARG_OCAMLDEP} )