[OCaml] Embed rpath into stub libraries and native executables

This commit embeds a set of linker flags with hardcoded paths to
the LLVM shared library on --enable-shared builds into .cmxa files
and stub dynamic libraries. This solution closely follows existing
rules for rpath in the LLVM tools, which had to be modified because
of differences in toolchain.

Without this patch, OCaml tests as well as opam bindings broke,
as neither of those updates LD_LIBRARY_PATH to include
the $prefix/lib directory.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195834 91177308-0d34-0410-b5e6-96231b3b80d8

bindings/ocaml/Makefile.ocaml

@@ -78,6 +78,15 @@ Compile.CMI  := $(strip $(OCAMLC) -c $(OCAMLCFLAGS) $(OCAMLDEBUGFLAG) -o)
 Compile.CMO  := $(strip $(OCAMLC) -c $(OCAMLCFLAGS) $(OCAMLDEBUGFLAG) -o)
 Compile.CMX  := $(strip $(OCAMLOPT) -c $(OCAMLCFLAGS) $(OCAMLDEBUGFLAG) -o)
 
+ifdef OCAMLSTUBS
+# Avoid the need for LD_LIBRARY_PATH
+ifneq ($(HOST_OS), $(filter $(HOST_OS), Cygwin MingW))
+ifneq ($(HOST_OS),Darwin)
+OCAMLRPATH   := $(RPATH) -Wl,'$(SharedLibDir)'
+endif
+endif
+endif
+
 ifdef OCAMLSTUBS
 Archive.CMA  := $(strip $(OCAMLC) -a -dllib -l$(LIBRARYNAME) $(OCAMLDEBUGFLAG) \
                                   -o)
@@ -88,8 +97,8 @@ endif
 
 ifdef OCAMLSTUBS
 Archive.CMXA := $(strip $(OCAMLOPT) -a $(patsubst %,-cclib %, \
-                                    $(LLVMLibsOptions) -l$(LIBRARYNAME)) \
-                                    -cclib -L$(SharedLibDir) \
+                                    $(LLVMLibsOptions) -l$(LIBRARYNAME) \
+                                    -L$(SharedLibDir) $(OCAMLRPATH))
                                     $(OCAMLDEBUGFLAG) -o)
 else
 Archive.CMXA := $(strip $(OCAMLOPT) -a $(OCAMLAFLAGS) $(OCAMLDEBUGFLAG) -o)
@@ -234,7 +243,7 @@ uninstall-local:: uninstall-shared
 
 $(SharedLib): $(ObjectsO) $(OcamlDir)/.dir
 	$(Echo) "Building $(BuildMode) $(notdir $@)"
-	$(Verb) $(Link) $(SharedLinkOptions) $(LLVMLibsOptions) \
+	$(Verb) $(Link) $(SharedLinkOptions) $(OCAMLRPATH) $(LLVMLibsOptions) \
 			-o $@ $(ObjectsO)
 
 clean-shared::